What s the best way to calculate the size of a directory in NET

Question

I ve written the following routine to manually traverse through a directory and calculate its size in C   NET     protected static float CalculateFolderSize string folder        float folderSize   0 0f      try                 Checks if the path is valid or not         if   Directory Exists folder               return folderSize          else                       try                               foreach  string file in Directory GetFiles folder                                         if  File Exists file                                                 FileInfo finfo   new FileInfo file                           folderSize    finfo Length                                                           foreach  string dir in Directory GetDirectories folder                       folderSize    CalculateFolderSize dir                             catch  NotSupportedException e                                Console WriteLine  Unable to calculate folder size   0    e Message                                     catch  UnauthorizedAccessException e                Console WriteLine  Unable to calculate folder size   0    e Message             return folderSize       I have an application which is running this routine repeatedly for a large number of folders   I m wondering if there s a more efficient way to calculate the size of a folder with  NET   I didn t see anything specific in the framework   Should I be using P Invoke and a Win32 API   What s the most efficient way of calculating the size of a folder in  NET

User · Accepted Answer

I do not believe there is a Win32 API to calculate the space consumed by a directory, although I stand to be corrected on this. If there were then I would assume Explorer would use it. If you get the Properties of a large directory in Explorer, the time it takes to give you the folder size is proportional to the number of files/sub-directories it contains.

Your routine seems fairly neat & simple. Bear in mind that you are calculating the sum of the file lengths, not the actual space consumed on the disk. Space consumed by wasted space at the end of clusters, file streams etc, are being ignored.

User · Answer

As far as the best algorithm goes you probably have it right  I would recommend that you unravel the recursive function and use a stack of your own  remember a stack overflow is the end of the world in a  Net 2 0  app  the exception can not be caught IIRC    The most important thing is that if you are using it in any form of a UI put it on a worker thread that signals the UI thread with updates

User · Answer

I extended  Hao s answer using the same counting principal but supporting richer data return  so you get back size  recursive size  directory count  and recursive directory count  N levels deep   public class DiskSizeUtil            lt summary gt          Calculate disk space usage under  lt paramref name  root   gt    If  lt paramref name  levels   gt  is provided           then return subdirectory disk usages as well  up to  lt paramref name  levels   gt  levels deep          If levels is not provided or is 0  return a list with a single element representing the         directory specified by  lt paramref name  root   gt            lt  summary gt           lt returns gt  lt  returns gt      public static FolderSizeInfo GetDirectorySize DirectoryInfo root  int levels   0                var currentDirectory   new FolderSizeInfo                Add file sizes          FileInfo   fis   root GetFiles            currentDirectory Size   0          foreach  FileInfo fi in fis                        currentDirectory Size    fi Length                        Add subdirectory sizes          DirectoryInfo   dis   root GetDirectories             currentDirectory Path   root          currentDirectory SizeWithChildren   currentDirectory Size          currentDirectory DirectoryCount   dis Length          currentDirectory DirectoryCountWithChildren   dis Length          currentDirectory FileCount   fis Length          currentDirectory FileCountWithChildren   fis Length           if  levels  gt   0              currentDirectory Children   new List lt FolderSizeInfo gt              foreach  DirectoryInfo di in dis                        var dd   GetDirectorySize di  levels - 1               if  levels  gt   0                  currentDirectory Children Add dd                currentDirectory SizeWithChildren    dd SizeWithChildren              currentDirectory DirectoryCountWithChildren    dd DirectoryCountWithChildren              currentDirectory FileCountWithChildren    dd FileCountWithChildren                     return currentDirectory             public class FolderSizeInfo               public DirectoryInfo Path   get  set            public long SizeWithChildren   get  set            public long Size   get  set            public int DirectoryCount   get  set            public int DirectoryCountWithChildren   get  set            public int FileCount   get  set            public int FileCountWithChildren   get  set            public List lt FolderSizeInfo gt  Children   get  set

User · Answer

No  this looks like the recommended way to calculate directory size  the relevent method included below   public static long DirSize DirectoryInfo d             long size   0             Add file sizes      FileInfo   fis   d GetFiles        foreach  FileInfo fi in fis                       size    fi Length                   Add subdirectory sizes      DirectoryInfo   dis   d GetDirectories        foreach  DirectoryInfo di in dis                 size    DirSize di                return size        You would call with the root as   Console WriteLine  The size is  0  bytes    DirSize new DirectoryInfo targetFolder         where targetFolder is the folder-size to calculate

User · Answer

public static long GetDirSize string path        try               return Directory EnumerateFiles path  Sum x   gt  new FileInfo x  Length                                 Directory EnumerateDirectories path  Sum x   gt  GetDirSize x              catch               return 0L

User · Answer

To improve the performance  you could use the Task Parallel Library  TPL   Here is a good sample  Directory file size calculation - how to make it faster   I didn t test it  but the author says it is 3 times faster than a non-multithreaded method

User · Answer

I ve been fiddling with VS2008 and LINQ up until recently and this compact and short method works great for me  example is in VB NET  requires LINQ    NET FW 3 5  of course    Dim size As Int64    From strFile In My Computer FileSystem GetFiles strFolder                  FileIO SearchOption SearchAllSubDirectories                  Select New System IO FileInfo strFile  Length  Sum     Its short  it searches sub-directories and is simple to understand if you know LINQ syntax  You could even specify wildcards to search for specific files using the third parameter of the  GetFiles function   I m not a C  expert but you can add the My namespace on C  this way   I think this way of obtaining a folder size is not only shorter and more modern than the way described on Hao s link  it basically uses the same loop-of-FileInfo method described there in the end

User · Answer

I try to change the sample  Alexandre Pepin and hao s Answer   As is      private long GetDirectorySize string dirPath                if  Directory Exists dirPath     false                        return 0                     DirectoryInfo dirInfo   new DirectoryInfo dirPath            long size   0              Add file sizes          FileInfo   fis   dirInfo GetFiles            foreach  FileInfo fi in fis                        size    fi Length                        Add subdirectory sizes          DirectoryInfo   dis   dirInfo GetDirectories            foreach  DirectoryInfo di in dis                        size    GetDirectorySize di FullName                      return size          To be      private long GetDirectorySize2 string dirPath                if  Directory Exists dirPath     false                        return 0                     DirectoryInfo dirInfo   new DirectoryInfo dirPath            long size   0              Add file sizes          IEnumerable lt FileInfo gt  fis   dirInfo EnumerateFiles        SearchOption AllDirectories           foreach  FileInfo fi in fis                        size    fi Length                     return size          finally you can check the result             ---------------------------------------------            size of directory         using System IO           string log1Path     D  SampleDirPath1           string log2Path     D  SampleDirPath2           string log1DirName   Path GetDirectoryName log1Path           string log2DirName   Path GetDirectoryName log2Path           long log1Size   GetDirectorySize log1Path           long log2Size   GetDirectorySize log2Path           long log1Size2   GetDirectorySize2 log1Path           long log2Size2   GetDirectorySize2 log2Path            Console WriteLine     log1DirName  Size   SizeSuffix log1Size     SizeSuffix log1Size2            log2DirName  Size   SizeSuffix log2Size     SizeSuffix log2Size2        and this is the SizeSuffix function      private static readonly string   SizeSuffixes                     bytes    KB    MB    GB    TB    PB    EB    ZB    YB               lt summary gt          Size Display          lt  summary gt           lt param name  value  gt bytes    lt  param gt           lt param name  decimalPlaces  gt      lt  param gt           lt returns gt  lt  returns gt      public static string SizeSuffix Int64 value  int decimalPlaces   2                if  decimalPlaces  lt  0    throw new ArgumentOutOfRangeException  decimalPlaces              if  value  lt  0    return  -    SizeSuffix -value             if  value    0    return string Format   0 n    decimalPlaces      bytes   0                 mag is 0 for bytes  1 for KB  2  for MB  etc          int mag    int Math Log value  1024               1L  lt  lt   mag   10     2    10   mag               i e  the number of bytes in the unit corresponding to mag          decimal adjustedSize    decimal value    1L  lt  lt   mag   10                make adjustment when the value is large enough that            it would round up to 1000 or more         if  Math Round adjustedSize  decimalPlaces   gt   1000                        mag    1              adjustedSize    1024                     return string Format   0 n    decimalPlaces       1                adjustedSize              SizeSuffixes mag

User · Answer

An alternative to Trikaldarshi s one line solution   It avoids having to construct FileInfo objects   long sizeInBytes   Directory EnumerateFiles   path        SearchOption AllDirectories  Sum fileInfo   gt  new FileInfo fileInfo  Length

User · Answer

I know this not a  net solution but here it comes anyways  Maybe it comes handy for people that have windows 10 and want a faster solution  For example if you run this command con your command prompt or by pressing winKey   R   bash -c  du -sh  mnt c Users   sleep 5        The sleep 5 is so you have time to see the results and the windows does not closes  In my computer that displays     Note at the end how it shows 85G  85 Gigabytes   It is supper fast compared to doing it with  Net  If you want to see the size more accurately remove the h which stands for human readable    So just do something like Processes Start  bash      arguments  That is not the exact code but you get the idea

User · Answer

More faster  Add COM reference  Windows Script Host Object      public double GetWSHFolderSize string Fldr                  Reference  Windows Script Host Object Model  on the COM tab          IWshRuntimeLibrary FileSystemObject FSO   new     IWshRuntimeLibrary FileSystemObject            double FldrSize    double FSO GetFolder Fldr  Size          Marshal FinalReleaseComObject FSO           return FldrSize        private void button1 Click object sender  EventArgs e                        string folderPath     C  Windows           Stopwatch sWatch   new Stopwatch             sWatch Start            double sizeOfDir   GetWSHFolderSize folderPath           sWatch Stop            MessageBox Show  Directory size in Bytes       sizeOfDir      Time      sWatch ElapsedMilliseconds ToString

User · Answer

This  NET core command line app here calculates directory sizes for a given path    https   github com garethrbrown folder-size  The key method is this one which recursively inspects sub-directories to come up with a total size   private static long DirectorySize SortDirection sortDirection  DirectoryInfo directoryInfo  DirectoryData directoryData            long directorySizeBytes   0              Add file sizes for current directory          FileInfo   fileInfos   directoryInfo GetFiles             foreach  FileInfo fileInfo in fileInfos                        directorySizeBytes    fileInfo Length                     directoryData Name   directoryInfo Name           directoryData SizeBytes    directorySizeBytes              Recursively add subdirectory sizes          DirectoryInfo   subDirectories   directoryInfo GetDirectories             foreach  DirectoryInfo di in subDirectories                        var subDirectoryData   new DirectoryData sortDirection                directoryData DirectoryDatas Add subDirectoryData                directorySizeBytes    DirectorySize sortDirection  di  subDirectoryData                      directoryData SizeBytes   directorySizeBytes           return directorySizeBytes

User · Answer

As far as the best algorithm goes you probably have it right  I would recommend that you unravel the recursive function and use a stack of your own  remember a stack overflow is the end of the world in a  Net 2 0  app  the exception can not be caught IIRC    The most important thing is that if you are using it in any form of a UI put it on a worker thread that signals the UI thread with updates

User · Answer

var size   new DirectoryInfo  E      GetDirectorySize      and here s the code behind this Extension method  public static long GetDirectorySize this System IO DirectoryInfo directoryInfo  bool recursive   true        var startDirectorySize   default long       if  directoryInfo    null     directoryInfo Exists          return startDirectorySize    Return 0 while Directory does not exist         Add size of files in the Current Directory to main size      foreach  var fileInfo in directoryInfo GetFiles            System Threading Interlocked Add ref startDirectorySize  fileInfo Length        if  recursive    Loop on Sub Direcotries in the Current Directory and Calculate it s files size          System Threading Tasks Parallel ForEach directoryInfo GetDirectories     subDirectory    gt      System Threading Interlocked Add ref startDirectorySize  GetDirectorySize subDirectory  recursive          return startDirectorySize     Return full Size of this Directory

User · Answer

The fastest way that I came up is using EnumerateFiles with SearchOption AllDirectories  This method also allows updating the UI while going through the files and counting the size  Long path names don t cause any problems since FileInfo or DirectoryInfo are not tried to be created for the long path name  While enumerating files even though the filename is long the FileInfo returned by the EnumerateFiles don t cause problems as long as the starting directory name is not too long  There is still a problem with UnauthorizedAccess       private void DirectoryCountEnumTest string sourceDirName                   Get the subdirectories for the specified directory          long dataSize   0          long fileCount   0          string prevText   richTextBox1 Text           if  Directory Exists sourceDirName                         DirectoryInfo dir   new DirectoryInfo sourceDirName               foreach  FileInfo file in dir EnumerateFiles      SearchOption AllDirectories                                 fileCount                    try                                       dataSize    file Length                      richTextBox1 Text   prevText      nCounting size      dataSize ToString                                       catch  Exception e                                        richTextBox1 AppendText   n    e Message                                               richTextBox1 AppendText   n files     fileCount ToString

User · Answer

This it the best way to calculate the size of a directory  Only other way would still use recursion but be a bit easier to use and isn t as flexible   float folderSize   0 0f  FileInfo   files   Directory GetFiles folder       SearchOption AllDirectories   foreach FileInfo file in files  folderSize    file Length

User · Answer

public static long DirSize DirectoryInfo dir        return dir GetFiles   Sum fi   gt  fi Length               dir GetDirectories   Sum di   gt  DirSize di

User · Answer

DirectoryInfo dirInfo   new DirectoryInfo  strDirPath   long dirSize   await Task Run      gt  dirInfo EnumerateFiles       SearchOption AllDirectories  Sum file   gt  file Length

User · Answer

An alternative to Trikaldarshi s one line solution   It avoids having to construct FileInfo objects   long sizeInBytes   Directory EnumerateFiles   path        SearchOption AllDirectories  Sum fileInfo   gt  new FileInfo fileInfo  Length

User · Answer

I know this not a  net solution but here it comes anyways  Maybe it comes handy for people that have windows 10 and want a faster solution  For example if you run this command con your command prompt or by pressing winKey   R   bash -c  du -sh  mnt c Users   sleep 5        The sleep 5 is so you have time to see the results and the windows does not closes  In my computer that displays     Note at the end how it shows 85G  85 Gigabytes   It is supper fast compared to doing it with  Net  If you want to see the size more accurately remove the h which stands for human readable    So just do something like Processes Start  bash      arguments  That is not the exact code but you get the idea

User · Answer

public static long GetDirSize string path        try               return Directory EnumerateFiles path  Sum x   gt  new FileInfo x  Length                                 Directory EnumerateDirectories path  Sum x   gt  GetDirSize x              catch               return 0L

User · Answer

As far as the best algorithm goes you probably have it right  I would recommend that you unravel the recursive function and use a stack of your own  remember a stack overflow is the end of the world in a  Net 2 0  app  the exception can not be caught IIRC    The most important thing is that if you are using it in any form of a UI put it on a worker thread that signals the UI thread with updates

User · Answer

I ve been fiddling with VS2008 and LINQ up until recently and this compact and short method works great for me  example is in VB NET  requires LINQ    NET FW 3 5  of course    Dim size As Int64    From strFile In My Computer FileSystem GetFiles strFolder                  FileIO SearchOption SearchAllSubDirectories                  Select New System IO FileInfo strFile  Length  Sum     Its short  it searches sub-directories and is simple to understand if you know LINQ syntax  You could even specify wildcards to search for specific files using the third parameter of the  GetFiles function   I m not a C  expert but you can add the My namespace on C  this way   I think this way of obtaining a folder size is not only shorter and more modern than the way described on Hao s link  it basically uses the same loop-of-FileInfo method described there in the end

User · Answer

this solution works very well  it s collecting all the sub folders   Directory GetFiles   MainFolderPath        SearchOption AllDirectories  Sum t   gt   new FileInfo t  Length

User · Answer

DirectoryInfo dirInfo   new DirectoryInfo  strDirPath   long dirSize   await Task Run      gt  dirInfo EnumerateFiles       SearchOption AllDirectories  Sum file   gt  file Length

User · Answer

this solution works very well  it s collecting all the sub folders   Directory GetFiles   MainFolderPath        SearchOption AllDirectories  Sum t   gt   new FileInfo t  Length

User · Answer

I extended  Hao s answer using the same counting principal but supporting richer data return  so you get back size  recursive size  directory count  and recursive directory count  N levels deep   public class DiskSizeUtil            lt summary gt          Calculate disk space usage under  lt paramref name  root   gt    If  lt paramref name  levels   gt  is provided           then return subdirectory disk usages as well  up to  lt paramref name  levels   gt  levels deep          If levels is not provided or is 0  return a list with a single element representing the         directory specified by  lt paramref name  root   gt            lt  summary gt           lt returns gt  lt  returns gt      public static FolderSizeInfo GetDirectorySize DirectoryInfo root  int levels   0                var currentDirectory   new FolderSizeInfo                Add file sizes          FileInfo   fis   root GetFiles            currentDirectory Size   0          foreach  FileInfo fi in fis                        currentDirectory Size    fi Length                        Add subdirectory sizes          DirectoryInfo   dis   root GetDirectories             currentDirectory Path   root          currentDirectory SizeWithChildren   currentDirectory Size          currentDirectory DirectoryCount   dis Length          currentDirectory DirectoryCountWithChildren   dis Length          currentDirectory FileCount   fis Length          currentDirectory FileCountWithChildren   fis Length           if  levels  gt   0              currentDirectory Children   new List lt FolderSizeInfo gt              foreach  DirectoryInfo di in dis                        var dd   GetDirectorySize di  levels - 1               if  levels  gt   0                  currentDirectory Children Add dd                currentDirectory SizeWithChildren    dd SizeWithChildren              currentDirectory DirectoryCountWithChildren    dd DirectoryCountWithChildren              currentDirectory FileCountWithChildren    dd FileCountWithChildren                     return currentDirectory             public class FolderSizeInfo               public DirectoryInfo Path   get  set            public long SizeWithChildren   get  set            public long Size   get  set            public int DirectoryCount   get  set            public int DirectoryCountWithChildren   get  set            public int FileCount   get  set            public int FileCountWithChildren   get  set            public List lt FolderSizeInfo gt  Children   get  set

User · Answer

To improve the performance  you could use the Task Parallel Library  TPL   Here is a good sample  Directory file size calculation - how to make it faster   I didn t test it  but the author says it is 3 times faster than a non-multithreaded method

User · Answer

It appears  that following method performs your task faster  than recursive function   long size   0  DirectoryInfo dir   new DirectoryInfo folder   foreach  FileInfo fi in dir GetFiles        SearchOption AllDirectories        size    fi Length      A simple console application test shows  that this loop sums files faster  than recursive function  and provides the same result  And you probably want to use LINQ methods  like Sum    to shorten this code

User · Answer

No  this looks like the recommended way to calculate directory size  the relevent method included below   public static long DirSize DirectoryInfo d             long size   0             Add file sizes      FileInfo   fis   d GetFiles        foreach  FileInfo fi in fis                       size    fi Length                   Add subdirectory sizes      DirectoryInfo   dis   d GetDirectories        foreach  DirectoryInfo di in dis                 size    DirSize di                return size        You would call with the root as   Console WriteLine  The size is  0  bytes    DirSize new DirectoryInfo targetFolder         where targetFolder is the folder-size to calculate

User · Answer

No  this looks like the recommended way to calculate directory size  the relevent method included below   public static long DirSize DirectoryInfo d             long size   0             Add file sizes      FileInfo   fis   d GetFiles        foreach  FileInfo fi in fis                       size    fi Length                   Add subdirectory sizes      DirectoryInfo   dis   d GetDirectories        foreach  DirectoryInfo di in dis                 size    DirSize di                return size        You would call with the root as   Console WriteLine  The size is  0  bytes    DirSize new DirectoryInfo targetFolder         where targetFolder is the folder-size to calculate

User · Answer

No  this looks like the recommended way to calculate directory size  the relevent method included below   public static long DirSize DirectoryInfo d             long size   0             Add file sizes      FileInfo   fis   d GetFiles        foreach  FileInfo fi in fis                       size    fi Length                   Add subdirectory sizes      DirectoryInfo   dis   d GetDirectories        foreach  DirectoryInfo di in dis                 size    DirSize di                return size        You would call with the root as   Console WriteLine  The size is  0  bytes    DirSize new DirectoryInfo targetFolder         where targetFolder is the folder-size to calculate

User · Answer

More faster  Add COM reference  Windows Script Host Object      public double GetWSHFolderSize string Fldr                  Reference  Windows Script Host Object Model  on the COM tab          IWshRuntimeLibrary FileSystemObject FSO   new     IWshRuntimeLibrary FileSystemObject            double FldrSize    double FSO GetFolder Fldr  Size          Marshal FinalReleaseComObject FSO           return FldrSize        private void button1 Click object sender  EventArgs e                        string folderPath     C  Windows           Stopwatch sWatch   new Stopwatch             sWatch Start            double sizeOfDir   GetWSHFolderSize folderPath           sWatch Stop            MessageBox Show  Directory size in Bytes       sizeOfDir      Time      sWatch ElapsedMilliseconds ToString

User · Answer

This it the best way to calculate the size of a directory  Only other way would still use recursion but be a bit easier to use and isn t as flexible   float folderSize   0 0f  FileInfo   files   Directory GetFiles folder       SearchOption AllDirectories   foreach FileInfo file in files  folderSize    file Length

User · Answer

This  NET core command line app here calculates directory sizes for a given path    https   github com garethrbrown folder-size  The key method is this one which recursively inspects sub-directories to come up with a total size   private static long DirectorySize SortDirection sortDirection  DirectoryInfo directoryInfo  DirectoryData directoryData            long directorySizeBytes   0              Add file sizes for current directory          FileInfo   fileInfos   directoryInfo GetFiles             foreach  FileInfo fileInfo in fileInfos                        directorySizeBytes    fileInfo Length                     directoryData Name   directoryInfo Name           directoryData SizeBytes    directorySizeBytes              Recursively add subdirectory sizes          DirectoryInfo   subDirectories   directoryInfo GetDirectories             foreach  DirectoryInfo di in subDirectories                        var subDirectoryData   new DirectoryData sortDirection                directoryData DirectoryDatas Add subDirectoryData                directorySizeBytes    DirectorySize sortDirection  di  subDirectoryData                      directoryData SizeBytes   directorySizeBytes           return directorySizeBytes

User · Answer

Multi thread example to calculate directory size from Microsoft Docs  which would be faster  using System  using System IO  using System Threading  using System Threading Tasks   public class Example      public static void Main              long totalSize   0         String   args   Environment GetCommandLineArgs          if  args Length    1             Console WriteLine  There are no command line arguments              return                if    Directory Exists args 1               Console WriteLine  The directory does not exist              return                 String   files   Directory GetFiles args 1          Parallel For 0  files Length                     index   gt    FileInfo fi   new FileInfo files index                                  long size   fi Length                                Interlocked Add ref totalSize  size                                 Console WriteLine  Directory   0      args 1          Console WriteLine   0 N0  files   1 N0  bytes   files Length  totalSize             The example displaysoutput like the following           Directory  c  windows             32 files  6 587 222 bytes   This example only calculate the files in current folder  so if you want to calculate all the files recursively  you can change the   String   files   Directory GetFiles args 1      to  String   files   Directory GetFiles args 1        SearchOption AllDirectories

User · Answer

The real question is  what do you intend to use the size for  Your first problem is that there are at least four definitions for  quot file size quot    The  quot end of file quot  offset  which is the number of bytes you have to skip to go from the beginning to the end of the file  In other words  it is the number of bytes logically in the file  from a usage perspective    The  quot valid data length quot   which is equal to the offset of the first byte which is not actually stored  This is always less than or equal to the  quot end of file quot   and is a multiple of the cluster size  For example  a 1 GB file can have a valid data length of 1 MB   If you ask Windows to read the first 8 MB  it will read the first 1 MB and pretend the rest of the data was there  returning it as zeros   The  quot allocated size quot  of a file  This is always greater than or equal to the  quot end of file quot   This is the number of clusters that the OS has allocated for the file  multiplied by the cluster size  Unlike the case where the  quot end of file quot  is greater than the  quot valid data length quot   The excess bytes are not considered to be part of the file s data  so the OS will not fill a buffer with zeros if you try to read in the allocated region beyond the end of the file   The  quot compressed size quot  of a file  which is only valid for compressed  and sparse   files  It is equal to the size of a cluster  multiplied by the number of clusters on the volume that are actually allocated to this file  For non-compressed and non-sparse files  there is no notion of  quot compressed size quot   you would use the  quot allocated size quot  instead    Your second problem is that a  quot file quot  like C  Foo can actually have multiple streams of data  This name just refers to the default stream  A file might have alternate streams  like C  Foo Bar  whose size is not even shown in Explorer  Your third problem is that a  quot file quot  can have multiple names   quot hard links quot    For example  C  Windows notepad exe and C  Windows System32 notepad exe are two names for the same file   Any name can be used to open any stream of the file  Your fourth problem is that a  quot file quot   or directory  might in fact not even be a file  or directory   It might be a soft link  a  quot symbolic link quot  or a  quot reparse point quot   to some other file  or directory   That other file might not even be on the same drive  It might even point to something on the network  or it might even be recursive  Should the size be infinity if it s recursive  Your fifth is that there are  quot filter quot  drivers that make certain files or directories look like actual files or directories  even though they aren t  For example  Microsoft s WIM image files  which are compressed  can be  quot mounted quot  on a folder using a tool called ImageX  and those do not look like reparse points or links  They look just like directories -- except that the re not actually directories  and the notion of  quot size quot  doesn t really make sense for them  Your sixth problem is that every file requires metadata  For example  having 10 names for the same file requires more metadata  which requires space  If the file names are short  having 10 names might be as cheap as having 1 name -- and if they re long  then having multiple names can use more disk space for the metadata   Same story with multiple streams  etc   Do you count these  too

User · Answer

The real question is  what do you intend to use the size for  Your first problem is that there are at least four definitions for  quot file size quot    The  quot end of file quot  offset  which is the number of bytes you have to skip to go from the beginning to the end of the file  In other words  it is the number of bytes logically in the file  from a usage perspective    The  quot valid data length quot   which is equal to the offset of the first byte which is not actually stored  This is always less than or equal to the  quot end of file quot   and is a multiple of the cluster size  For example  a 1 GB file can have a valid data length of 1 MB   If you ask Windows to read the first 8 MB  it will read the first 1 MB and pretend the rest of the data was there  returning it as zeros   The  quot allocated size quot  of a file  This is always greater than or equal to the  quot end of file quot   This is the number of clusters that the OS has allocated for the file  multiplied by the cluster size  Unlike the case where the  quot end of file quot  is greater than the  quot valid data length quot   The excess bytes are not considered to be part of the file s data  so the OS will not fill a buffer with zeros if you try to read in the allocated region beyond the end of the file   The  quot compressed size quot  of a file  which is only valid for compressed  and sparse   files  It is equal to the size of a cluster  multiplied by the number of clusters on the volume that are actually allocated to this file  For non-compressed and non-sparse files  there is no notion of  quot compressed size quot   you would use the  quot allocated size quot  instead    Your second problem is that a  quot file quot  like C  Foo can actually have multiple streams of data  This name just refers to the default stream  A file might have alternate streams  like C  Foo Bar  whose size is not even shown in Explorer  Your third problem is that a  quot file quot  can have multiple names   quot hard links quot    For example  C  Windows notepad exe and C  Windows System32 notepad exe are two names for the same file   Any name can be used to open any stream of the file  Your fourth problem is that a  quot file quot   or directory  might in fact not even be a file  or directory   It might be a soft link  a  quot symbolic link quot  or a  quot reparse point quot   to some other file  or directory   That other file might not even be on the same drive  It might even point to something on the network  or it might even be recursive  Should the size be infinity if it s recursive  Your fifth is that there are  quot filter quot  drivers that make certain files or directories look like actual files or directories  even though they aren t  For example  Microsoft s WIM image files  which are compressed  can be  quot mounted quot  on a folder using a tool called ImageX  and those do not look like reparse points or links  They look just like directories -- except that the re not actually directories  and the notion of  quot size quot  doesn t really make sense for them  Your sixth problem is that every file requires metadata  For example  having 10 names for the same file requires more metadata  which requires space  If the file names are short  having 10 names might be as cheap as having 1 name -- and if they re long  then having multiple names can use more disk space for the metadata   Same story with multiple streams  etc   Do you count these  too

User · Answer

It appears  that following method performs your task faster  than recursive function   long size   0  DirectoryInfo dir   new DirectoryInfo folder   foreach  FileInfo fi in dir GetFiles        SearchOption AllDirectories        size    fi Length      A simple console application test shows  that this loop sums files faster  than recursive function  and provides the same result  And you probably want to use LINQ methods  like Sum    to shorten this code

User · Answer

Directory GetFiles   C  Users AliBayat      SearchOption AllDirectories   Select  d   gt  new FileInfo d    Select  d   gt  new   Directory   d DirectoryName FileSize   d Length     ToLookup  d   gt  d Directory    Select  d   gt  new   Directory   d Key TotalSizeInMB  Math Round d Select  x   gt x FileSize   Sum     Math Pow 1024 0 2  2     OrderByDescending  d   gt  d TotalSizeInMB  ToList      Calling GetFiles with SearchOption AllDirectories returns the full name of all the files in all the subdirectories of the specified directory  The OS represents the size of files in bytes  You can retrieve the file   s size from its Length property  Dividing it by 1024 raised to the power of 2 gives you the size of the file in megabytes  Because a directory folder can contain many files  d Select x   gt  x FileSize  returns a collection of file sizes measured in megabytes  The final call to Sum   finds the total size of the files in the specified directory   Update  the filterMask     does not work with files without extension

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The fastest way that I came up is using EnumerateFiles with SearchOption AllDirectories  This method also allows updating the UI while going through the files and counting the size  Long path names don t cause any problems since FileInfo or DirectoryInfo are not tried to be created for the long path name  While enumerating files even though the filename is long the FileInfo returned by the EnumerateFiles don t cause problems as long as the starting directory name is not too long  There is still a problem with UnauthorizedAccess       private void DirectoryCountEnumTest string sourceDirName                   Get the subdirectories for the specified directory          long dataSize   0          long fileCount   0          string prevText   richTextBox1 Text           if  Directory Exists sourceDirName                         DirectoryInfo dir   new DirectoryInfo sourceDirName               foreach  FileInfo file in dir EnumerateFiles      SearchOption AllDirectories                                 fileCount                    try                                       dataSize    file Length                      richTextBox1 Text   prevText      nCounting size      dataSize ToString                                       catch  Exception e                                        richTextBox1 AppendText   n    e Message                                               richTextBox1 AppendText   n files     fileCount ToString

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I try to change the sample  Alexandre Pepin and hao s Answer   As is      private long GetDirectorySize string dirPath                if  Directory Exists dirPath     false                        return 0                     DirectoryInfo dirInfo   new DirectoryInfo dirPath            long size   0              Add file sizes          FileInfo   fis   dirInfo GetFiles            foreach  FileInfo fi in fis                        size    fi Length                        Add subdirectory sizes          DirectoryInfo   dis   dirInfo GetDirectories            foreach  DirectoryInfo di in dis                        size    GetDirectorySize di FullName                      return size          To be      private long GetDirectorySize2 string dirPath                if  Directory Exists dirPath     false                        return 0                     DirectoryInfo dirInfo   new DirectoryInfo dirPath            long size   0              Add file sizes          IEnumerable lt FileInfo gt  fis   dirInfo EnumerateFiles        SearchOption AllDirectories           foreach  FileInfo fi in fis                        size    fi Length                     return size          finally you can check the result             ---------------------------------------------            size of directory         using System IO           string log1Path     D  SampleDirPath1           string log2Path     D  SampleDirPath2           string log1DirName   Path GetDirectoryName log1Path           string log2DirName   Path GetDirectoryName log2Path           long log1Size   GetDirectorySize log1Path           long log2Size   GetDirectorySize log2Path           long log1Size2   GetDirectorySize2 log1Path           long log2Size2   GetDirectorySize2 log2Path            Console WriteLine     log1DirName  Size   SizeSuffix log1Size     SizeSuffix log1Size2            log2DirName  Size   SizeSuffix log2Size     SizeSuffix log2Size2        and this is the SizeSuffix function      private static readonly string   SizeSuffixes                     bytes    KB    MB    GB    TB    PB    EB    ZB    YB               lt summary gt          Size Display          lt  summary gt           lt param name  value  gt bytes    lt  param gt           lt param name  decimalPlaces  gt      lt  param gt           lt returns gt  lt  returns gt      public static string SizeSuffix Int64 value  int decimalPlaces   2                if  decimalPlaces  lt  0    throw new ArgumentOutOfRangeException  decimalPlaces              if  value  lt  0    return  -    SizeSuffix -value             if  value    0    return string Format   0 n    decimalPlaces      bytes   0                 mag is 0 for bytes  1 for KB  2  for MB  etc          int mag    int Math Log value  1024               1L  lt  lt   mag   10     2    10   mag               i e  the number of bytes in the unit corresponding to mag          decimal adjustedSize    decimal value    1L  lt  lt   mag   10                make adjustment when the value is large enough that            it would round up to 1000 or more         if  Math Round adjustedSize  decimalPlaces   gt   1000                        mag    1              adjustedSize    1024                     return string Format   0 n    decimalPlaces       1                adjustedSize              SizeSuffixes mag

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Multi thread example to calculate directory size from Microsoft Docs  which would be faster  using System  using System IO  using System Threading  using System Threading Tasks   public class Example      public static void Main              long totalSize   0         String   args   Environment GetCommandLineArgs          if  args Length    1             Console WriteLine  There are no command line arguments              return                if    Directory Exists args 1               Console WriteLine  The directory does not exist              return                 String   files   Directory GetFiles args 1          Parallel For 0  files Length                     index   gt    FileInfo fi   new FileInfo files index                                  long size   fi Length                                Interlocked Add ref totalSize  size                                 Console WriteLine  Directory   0      args 1          Console WriteLine   0 N0  files   1 N0  bytes   files Length  totalSize             The example displaysoutput like the following           Directory  c  windows             32 files  6 587 222 bytes   This example only calculate the files in current folder  so if you want to calculate all the files recursively  you can change the   String   files   Directory GetFiles args 1      to  String   files   Directory GetFiles args 1        SearchOption AllDirectories

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public static long DirSize DirectoryInfo dir        return dir GetFiles   Sum fi   gt  fi Length               dir GetDirectories   Sum di   gt  DirSize di

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Directory GetFiles   C  Users AliBayat      SearchOption AllDirectories   Select  d   gt  new FileInfo d    Select  d   gt  new   Directory   d DirectoryName FileSize   d Length     ToLookup  d   gt  d Directory    Select  d   gt  new   Directory   d Key TotalSizeInMB  Math Round d Select  x   gt x FileSize   Sum     Math Pow 1024 0 2  2     OrderByDescending  d   gt  d TotalSizeInMB  ToList      Calling GetFiles with SearchOption AllDirectories returns the full name of all the files in all the subdirectories of the specified directory  The OS represents the size of files in bytes  You can retrieve the file   s size from its Length property  Dividing it by 1024 raised to the power of 2 gives you the size of the file in megabytes  Because a directory folder can contain many files  d Select x   gt  x FileSize  returns a collection of file sizes measured in megabytes  The final call to Sum   finds the total size of the files in the specified directory   Update  the filterMask     does not work with files without extension

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As far as the best algorithm goes you probably have it right  I would recommend that you unravel the recursive function and use a stack of your own  remember a stack overflow is the end of the world in a  Net 2 0  app  the exception can not be caught IIRC    The most important thing is that if you are using it in any form of a UI put it on a worker thread that signals the UI thread with updates

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var size   new DirectoryInfo  E      GetDirectorySize      and here s the code behind this Extension method  public static long GetDirectorySize this System IO DirectoryInfo directoryInfo  bool recursive   true        var startDirectorySize   default long       if  directoryInfo    null     directoryInfo Exists          return startDirectorySize    Return 0 while Directory does not exist         Add size of files in the Current Directory to main size      foreach  var fileInfo in directoryInfo GetFiles            System Threading Interlocked Add ref startDirectorySize  fileInfo Length        if  recursive    Loop on Sub Direcotries in the Current Directory and Calculate it s files size          System Threading Tasks Parallel ForEach directoryInfo GetDirectories     subDirectory    gt      System Threading Interlocked Add ref startDirectorySize  GetDirectorySize subDirectory  recursive          return startDirectorySize     Return full Size of this Directory

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This it the best way to calculate the size of a directory  Only other way would still use recursion but be a bit easier to use and isn t as flexible   float folderSize   0 0f  FileInfo   files   Directory GetFiles folder       SearchOption AllDirectories   foreach FileInfo file in files  folderSize    file Length

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This it the best way to calculate the size of a directory  Only other way would still use recursion but be a bit easier to use and isn t as flexible   float folderSize   0 0f  FileInfo   files   Directory GetFiles folder       SearchOption AllDirectories   foreach FileInfo file in files  folderSize    file Length

[c#] What's the best way to calculate the size of a directory in .NET?

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