What is the difference between baud rate and bit rate

Question

I am really having hard time understanding the difference  Some say they are same  while others say there is a slight difference  What s the difference  exactly  I would like it if you explained with some analogy

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Bit rate is a measure of the number of data bits (that's 0's and 1's) transmitted in one second. A figure of 2400 bits per second means 2400 zeros or ones can be transmitted in one second, hence the abbreviation 'bps'.

Baud rate by definition means the number of times a signal in a communications channel changes state. For example, a 2400 baud rate means that the channel can change states up to 2400 times per second. When I say 'change state' I mean that it can change from 0 to 1 up to 2400 times per second. If you think about this, it's pretty much similar to the bit rate, which in the above example was 2400 bps.

Whether you can transmit 2400 zeros or ones in one second (bit rate), or change the state of a digital signal up to 2400 times per second (baud rate), it the same thing.

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First something I think necessary to know   It is symbol that is transferred on a physical channel  Not bit  Symbol is the physical signals that is transferred over the physical medium to convey the data bits  A symbol can be one of several voltage  frequency  or phase changes  Symbol is decided by the physical nature of the medium  While bit is a logical concept   If you want to transfer data bits  you must do it by sending symbols over the medium  Baud rate describes how fast symbols change over a medium  I e  it describes the rate of physical state changes over the medium   If we use only 2 symbols to transfer binary data  which means one symbol for 0 and another symbol for 1  that will lead to baud rate   bit rate  And this is how it works in the old days   If we are lucky enough to find a way to encode more bits into a symbol  we can achieve higher bit rate with the same baud rate  And this is when the baud rate  lt  bit rate  This doesn t mean the transfer speed is slowed down  It actually means the transfer efficiency speed is increased   And the communicating parties have to agree on how bits are represented by each physical symbol  This is where the modulation protocols come in   But the ability of sending multiple bits per symbol doesn t come free  The transmitter and receiver will be complex depending on the modulation methods  And more processing power is required   Finally  I d like to make an analogy   Suppose I stand on the roof of my house and you stand on your roof  There s a rope between you and me  I want to send some apples to you through a basket down the rope    The basket is the symbol  The apple is the data bits   If the basket is small  a physical limitation of the symbol   I may only send one apple per basket  This is when baud basket rate   bit apple rate   If the basket is big  I can send more apples per basket  This is when baud rate  lt  bit rate  I can send all the apples with less baskets  But it takes me more effort  processing power  to put more apples into the basket than put just one apple  If the basket rate remains the same  the more apples I put in one basket  the less time it takes   Here are some related threads   How can I be sure that a multi-bit-per-symbol encoding schema exists   What is difference between the terms bit rate baud rate and data rate

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Bits per second is straightforward  It is exactly what it sounds like  If I have 1000 bits and am sending them at 1000 bps  it will take exactly one second to transmit them   Baud is symbols per second  If these symbols     the indivisible elements of your data encoding     are not bits  the baud rate will be lower than the bit rate by the factor of bits per symbol  That is  if there are 4 bits per symbol  the baud rate will be  frac14  that of the bit rate   This confusion arose because the early analog telephone modems weren t very complicated  so bps was equal to baud  That is  each symbol encoded one bit  Later  to make modems faster  communications engineers invented increasingly clever ways to send more bits per symbol     Analogy  System 1  bits  Imagine a communication system with a telescope on the near side of a valley and a guy on the far side holding up one hand or the other  Call his left hand  0  and his right hand  1   and you have a system for communicating one binary digit     one bit     at a time   System 2  baud  Now imagine that the guy on the far side of the valley is holding up playing cards instead of his bare hands  He is using a subset of the cards  ace through 8 in each suit  for a total of 32 cards  Each card  mdash  each symbol  mdash  encodes 5 bits  00000 through 11111 in binary     Analysis  The System 2 guy can convey 5 bits of information per card in the same time it takes the System 1 guy to convey one bit by revealing one of his bare hands   You see how the analogy seems to break down  finding a particular card in a deck and showing it takes longer than simply deciding to show your left or right hand  But  that just provides an opportunity to extend the analogy profitably   A communications system with many bits per symbol faces a similar difficulty  because the encoding schemes required to send multiple bits per symbol are much more complicated than those that send only one bit at a time  To extend the analogy  then  the guy showing playing cards could have several people behind him sharing the work of finding the next card in the deck  handing him cards as fast as he can show them  The helpers are analogous to the more powerful processors required to produce the many-bits-per-baud encoding schemes   That is to say  by using more processing power  System 2 can send data 5 times faster than the more primitive System 1   Historical Vignette  What shall we do with our 5-bit code  It seems natural to an English speaker to use 26 of the 32 available code points for the English alphabet  We can use the remaining 6 code points for a space character and a small set of control codes and symbols    Or  we could just use Baudot code  a 5-bit code invented by   mile Baudot  after whom the unit  baud  was coined       Footnotes and Digressions    For example  the V 34 standard defined a 3 429 baud mode at 8 4 bits per symbol to achieve 28 8 nbsp kbit sec throughput   That standard only talks about the POTS side of the modem  The RS-232 side remains a 1 bit per symbol system  so you could also correctly call it a 28 8k baud modem  Confusing  but technically correct  I ve purposely kept things simple here    One thing you might think about is whether the absence of a playing card conveys information  If it does  that implies the existence of some clock or latch signal  so that you can tell the information-carrying absence of a card from the gap between the display of two cards   Also  what do you do with the cards left over in a poker deck  9 through King  and the Jokers  One idea would be to use them as special flags to carry metadata  For example  you ll need a way to indicate a short trailing block  If you need to send 128 bits of information  you re going to need to show 26 cards  The first 25 cards convey 5 times 25 125 bits  with the 26th card conveying the trailing 3 bits  You need some way to signal that the last two bits in the symbol should be disregarded  This is why the early analog telephone modems were specified in terms of baud instead of bps  communications engineers had been using that terminology since the telegraph days  They weren t trying to confuse bps and baud  it was simply a fact  in their minds  that these modems were transmitting one bit per symbol

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Baud rate is mostly used in telecommunication and electronics  representing symbol per second or pulses per second  whereas bit rate is  simply bit per second  To be simple  the major difference is that symbol may contain more than 1 bit  say n bits  which makes baud rate n times smaller than bit rate   Suppose a situation where we need to represent a serial-communication signal  we will use 8-bit as one symbol to represent the info  If the symbol rate is 4800 baud  then that translates into an overall bit rate of 38400 bits s  This could also be true for wireless communication area where you will need multiple bits for purpose of modulation to achieve broadband transmission  instead of simple baseline transmission   Hope this helps

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Bit rate -       Bit rate is nothing but number of bits transmitted per second For example if Bit rate is 1000bps then 1000 bits are i e  0s or 1s transmitted per second   Baud rate -       It means number of time signal changes its state When the signal is binary then baud rate and bit rate are same

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The bit rate is a measure of the number of bits that are transmitted per unit of time   The baud rate  which is also known as symbol rate  measures the number of symbols that are transmitted per unit of time  A symbol typically consists of a fixed number of bits depending on what the symbol is defined as for example 8bit or 9bit data   The baud rate is measured in symbols per second   Take an example  where an ascii character  R  is transmitted over a serial channel every one second   The binary equivalent is 01010010   So in this case  the baud rate is 1 one symbol transmitted per second  and the bit rate is 8  eight bits are transmitted per second

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Bit per second is what is means - rate of data transmission of ones and zeros per second are used This is called bit per second bit s  However  it should not be confused with bytes per second  abbreviated as bytes s  Bps  or B s   Raw throughput values are normally given in bits per second  but many software applications report transfer rates in bytes per second   So  the standard unit for bit throughput is the bit per second  which is commonly abbreviated bit s  bps  or b s   Baud is a unit of measure of changes   or transitions   that occurs in a signal in each second   For example if the signal changes from one value to a zero value or vice versa  one hundred times per second  that is a rate of 100 baud   The other one measures data the throughput of channel   and the other ones measures transitions called signalling rates    For example if you look at modern modems they use advanced modulation techniques that encoded more than one bit of data into each transition   Thanks

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This topic is confusing because there are 3 terms in use when people think there are just 2  namely    bit rate   units are bits per second   baud   units are symbols per second   Baud rate   units are bits per second   Baud rate  is really a marketing term rather than an engineering term   Baud rate  was used by modem manufactures in a similar way to megapixels is used for digital cameras  So the higher the  Baud rate  the better the modem was perceived to be   The engineering unit  baud  is already a rate  symbols per second  which distinguishes it from the  Baud rate  term  However  you can see from the answers that people are confusing these 2 terms together such as baud sec which is wrong   From an engineering point of view  I recommend people use the term  bit rate  for  RS-232  and consign to history the term  Baud rate   Use the term  baud  for modulation schemes but avoid it for  RS-232    In other words   bit rate  and  Baud rate  are the same thing which means how many bits are transmitted along a wire in one second  Note that bits per second  bps  is the low-level line rate and not the information data rate because asynchronous  RS-232  has start and stop bits that frame the 8 data bits of information so bps includes all bits transmitted

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Serial Data Speed   Data rate  bps    1 Tb  Tb is the time duration of 1 bit  If the bit duration is 2ms then data rate is 1 2x10-3   which is about 500 bps   Baud rate   Baud rate is defined as no  of signalling elements symbols  in a given unit of time  say 1 sec  or it means number of time signal changes its state When the signal is binary then baud rate and bit rate are same   Bit rate - Bit rate is nothing but number of bits transmitted per second For example if Bit rate is 1000 bps then 1000 bits are i e  0s or 1s transmitted per second   There are few other terms similar to this  i e serial speed  bit rate  baud rate  USB transfer rate  and i guess    the values that are printed on serial monitor relates to serial speed  baud rate and USB transfer rate  Bit rate isn t an another term  please correct me if i am wrong  because serial monitor prints some values at an interval of time and value is definitely a set of bits  so if one value is printed i can say no of bits present in the respective value which gets printed on serial monitor per unit time will be the bit rate

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According to What   s The Difference Between Bit Rate And Baud Rate       Bit Rate      The speed of the data is expressed in bits per second  bits s or bps     The data rate R is a function of the duration of the bit or bit time    TB   Fig  1  again        R   1 TB      Rate is also called channel capacity C  If the bit time is 10 ns  the   data rate equals       R   1 10 x 10   9   100 million bits s      This is usually expressed as 100 Mbits s       Baud Rate      The term    baud    originates from the French engineer Emile Baudot  who   invented the 5-bit teletype code  Baud rate refers to the number of   signal or symbol changes that occur per second  A symbol is one of   several voltage  frequency  or phase changes       NRZ binary has two symbols  one for each bit 0 or 1  that represent   voltage levels  In this case  the baud or symbol rate is the same as   the bit rate  However  it   s possible to have more than two symbols per   transmission interval  whereby each symbol represents multiple bits    With more than two symbols  data is transmitted using modulation   techniques       When the transmission medium can   t handle the baseband data    modulation enters the picture  Of course  this is true of wireless    Baseband binary signals can   t be transmitted directly  rather  the   data is modulated on to a radio carrier for transmission  Some cable   connections even use modulation to increase the data rate  which is   referred to as    broadband transmission          By using multiple symbols  multiple bits can be transmitted per   symbol  For example  if the symbol rate is 4800 baud and each symbol   represents two bits  that translates into an overall bit rate of 9600   bits s  Normally the number of symbols is some power of two  If N is   the number of bits per symbol  then the number of required symbols is   S   2 N  Thus  the gross bit rate is       R   baud rate x log2S   baud rate x 3 32 log10S      If the baud rate is 4800 and there are two bits per symbol  the number   of symbols is 2 2   4  The bit rate is       R   4800 x 3 32 log 4    4800 x 2   9600 bits s      If there   s only one bit per symbol  as is the case with binary NRZ    the bit and baud rates remain the same

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bit rate   no of bits 0 or 1 for binary signal  transmitted per second   baud rate    no of symbols per second   A symbol consists of  n  number of bits   Baud rate    bit rate  n  So baud rate is always less than or equal to bit rate It is equal when signal is binary

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I don t understand why everyone is making this complicated  answers     I ll just leave this here     So above would be    Signal Unit  4 bits Baud Rate  Signal Units per second   1000 Bd  baud  Bit Rate  Baud Rate   Signal Unit   4000 bps  bits per second       Bit rate and Baud rate  these two terms are often used in data   communication  Bit rate is simply the number of bits  i e   0   s and   1   s  transmitted per unit time  While Baud rate is the number of   signal units transmitted per unit time that is needed to represent   those bits

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Replies here are misleading  Saying true  but no one tell that for UART a symbol is not a single character but a single bit and this way the question was tagged  For example 115200 8n1 is 11520 bytes per second as a single ASCII character is a 1 start bit plus 8 data bit plus 1 stop bit

[microcontroller] What is the difference between baud rate and bit rate?

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