List of standard lengths for database fields

Question

I m designing a database table and once again asking myself the same stupid question  How long should the firstname field be   Does anyone have a list of reasonable lengths for the most common fields  such as first name  last name  and email address

User · Answer

I pretty much always use a power of 2 unless there is a good reason not to, such as a customer facing interface where some other number has special meaning to the customer.

If you stick to powers of 2 it keeps you within a limited set of common sizes, which itself is a good thing, and it makes it easier to guess the size of unknown objects you may encounter. I see a fair number of other people doing this, and there is something aesthetically pleasing about it. It generally gives me a good feeling when I see this, it means the designer was thinking like an engineer or mathematician. Though I'd probably be concerned if only prime numbers were used. :)

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it is varchar right  So it then doesn t matter if you use 50 or 25  better be safe and use 50  that said I believe the longest I have seen is about 19 or so  Last names are longer

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W3C s recommendation      If designing a form or database that will accept names from people   with a variety of backgrounds  you should ask yourself whether you   really need to have separate fields for given name and family name           Bear in mind that names in some cultures can be quite a lot longer   than your own      Avoid limiting the field size for names in your   database  In particular  do not assume that a four-character   Japanese name in UTF-8 will fit in four bytes     you are likely to   actually need 12       https   www w3 org International questions qa-personal-names   For database fields  VARCHAR 255  is a safe default choice  unless you can actually come up with a good reason to use something else  For typical web applications  performance won t be a problem  Don t prematurely optimize

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If you need to consider localisation  for those of us outside the US   and it s possible in your environment  I d suggest   Define data types for each component of the name - NOTE  some cultures have more than two names  Then have a type for the full name   Then localisation becomes simple  as far as names are concerned    The same applies to addresses  BTW - different formats

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------------ --------------- ---------------------------------      Field      Length  Char              Description              ------------ --------------- ---------------------------------   firstname     35                                                 lastname      35                                                 email         255                                                url           60              According to server and browser    city          45                                                 address       90                                                 ------------ --------------- ---------------------------------    Edit  Added some spacing

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Just looking though my email archives  there are a number of pretty long  first  names  of course what is meant by first is variable by culture    One example is Krishnamurthy - which is 13 letters long   A good guess might be 20 to 25 letters based on this   Email should be much longer since you might have firstname lastname somedomain com   Also  gmail and some other mail programs allow you to use firstname lastname sometag somedomain com where  sometag  is anything you want to put there so that you can use it to sort incoming emails   I frequently run into web forms that don t allow me to put in my full email address without considering any tags    So  if you need a fixed email field maybe something like  25 25 15 20 3 in characters for a total of 90 characters  if I did my math right

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I would say to err on the high side   Since you ll probably be using varchar  any extra space you allow won t actually use up any extra space unless somebody needs it   I would say for names  first or last   go at least 50 chars  and for email address  make it at least 128   There are some really long email addresses out there     Another thing I like to do is go to Lipsum com and ask it to generate some text   That way you can get a good idea of just what 100 bytes looks like

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Some probably correct column lengths                              Min Max  Hostname                    1   255 Domain Name                 4   253 Email Address               7   254 Email Address  1            3   254 Telephone Number            10  15       Telephone Number  2         3   26   HTTP S  URL w domain name   11  2083         URL  3                      6   2083     Postal Code  4              2   11 IP Address  incl ipv6       7   45 Longitude                   numeric 9 6 Latitude                    numeric 8 6 Money 5                     numeric 19 4   1  Allow local domains or TLD-only domains  2  Allow short numbers like 911 and extensions like 16045551212x12345  3  Allow local domains  tv    scheme  4  http   en wikipedia org wiki List of postal codes  Use max 12 if storing dash or space  5  http   stackoverflow com questions 224462 storing-money-in-a-decimal-column-what-precision-and-scale   A long rant on personal names  A personal name is either a Polynym  a name with multiple sortable components   a Mononym  a name with only one component   or a Pictonym  a name represented by a picture - this exists due to people like Prince    A person can have multiple names  playing roles  such as LEGAL  MARITAL  MAIDEN  PREFERRED  SOBRIQUET  PSEUDONYM  etc  You might have business rules  such as  a person can only have one legal name at a time  but multiple pseudonyms at a time     Some examples   names            type  POLYNYM       role  LEGAL       given  George       middle  Herman       moniker  Babe       surname  Ruth       generation  JUNIOR               type  MONONYM       role  SOBRIQUET       mononym  The Bambino     mononyms can be more than one word  but only one component                 type  MONONYM       role  SOBRIQUET       mononym  The Sultan of Swat          or  names            type  POLYNYM       role  PREFERRED       given  Malcolm       surname  X               type  POLYNYM       role  BIRTH       given  Malcolm       surname  Little               type  POLYNYM       role  LEGAL       given  Malik       surname  El-Shabazz          or  names           type  POLYNYM       role  LEGAL       given  Prince       middle  Rogers       surname  Nelson               type  MONONYM       role  SOBRIQUET       mononym  Prince               type  PICTONYM       role  LEGAL       url  http   upload wikimedia org wikipedia en thumb a af Prince logo svg 130px-Prince logo svg png          or  names           type  POLYNYM       role  LEGAL       given  Juan Pablo       surname  Fern  ndez de Calder  n       secondarySurname  Garc  a-Iglesias     hispanic people often have two surnames  it can be impolite to use the wrong one  Portuguese and Spaniards differ as to which surname is important            Given names  middle names  surnames can be multiple words such as  Billy Bob  Thornton  or Ralph  Vaughn Williams

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I usually go with   Firstname  30 chars Lastname  30 chars Email  50 chars Address  200 chars  If I am concerned about long fields for the names  I might sometimes go with 50 for the name fields too  since storage space is rarely an issue these days

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UK Government Data Standards Catalogue details the UK standards for this kind of thing  It suggests 35 characters for each of Given Name and Family Name  or 70 characters for a single field to hold the Full Name  and 255 characters for an email address   Amongst other things

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These might be useful to someone   youtube max channel length   20 facebook max name length     50 twitter max handle length    15 email max length             255    http   www interoadvisory com 2015 08 6-areas-inside-of-linkedin-with-character-limits

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I wanted to find the same and the UK Government Data Standards mentioned in the accepted answer sounded ideal  However none of these seemed to exist any more - after an extended search I found it in an archive here  http   webarchive nationalarchives gov uk   http   www cabinetoffice gov uk govtalk schemasstandards e-gif datastandards aspx  Need to download the zip  extract it and then open default htm in the html folder

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I just queried my database with millions of customers in the USA    The maximum first name length was 46   I go with 50   Of course  only 500 of those were over 25  and they were all cases where data imports resulted in extra junk winding up in that field   Last name was similar to first name  Email addresses maxed out at 62 characters   Most of the longer ones were actually lists of email addresses separated by semicolons  Street address maxes out at 95 characters   The long ones were all valid  Max city length was 35    This should be a decent statistical spread for people in the US   If you have localization to consider  the numbers could vary significantly

[database] List of standard lengths for database fields

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