What Is Baud?

Date First Published: 17th May 2022

Topic: Computer Networking

Subtopic: Data Transmission Technologies

Article Type: Computer Terms & Definitions

Difficulty Level: 7/10

Learn more about what baud is in this article.

Baud, also known as baud rate, is a unit that is used to give a measure of the communication speed over a data channel. It is equal to the number of times a signal changes state in the transmission medium per second in a digitally modulated signal. It has the same meaning as symbols per second or pulses per second.

Note:

One baud is equivalent to 1 bit per second for signals with only two possible states, meaning that there are exactly two symbols in the system (often 0 an 1). However, most modem transfer multiple bits per signal transmission.

Other units of baud exist, which refers to larger measurements. Examples include:

• 1 Kilobaud (kBd) = 1000 Baud
• 1 Megabaud (mBd) = 1000 Kilobaud
• 1 Gigabaud (gBd) = 1000 Megabaud

How To Calculate Baud Rate?

Baud rate can be calculated using this formula.

Data transfer rate (bits) ÷ number of bits per signal transmission = baud rate

For example, if a 56 Kb/s dial-up modem sends 7 bits per signal transmission, the calculation would be:

56,000 ÷ 7 = 8000 baud

Note that the kilobits have been converted to bits.

The calculation for converting baud to data transfer rate is:

Communication speed (baud rate) x number of bits per signal transmission = data transfer rate

For example, if a modem with a baud rate of 2100 sends 6 bits per signal transmission, the calculation would be:

2100 x 9 = 12,600 B/s.

In order to convert this into kilobits, the calculation would be:

12,600 ÷ 1024 = 12.3 (rounded to 1 decimal place)

Data transfer rate = 12.3 Kb/s

What Is The Maximum Baud Rate?

Usually, modems automatically select the most efficient baud rate. However, most dial-up modems allow the default baud setting to be overwritten and manually entered through the use of a software interface, which is helpful if an ISP requires a certain baud rate for communication. Reducing the baud rate of a modem will cause its data transfer rate to drop.

Baud rates above 8000 are unreliable on analogue telephone lines. This is because only 7 bits can be sent at the same time with each pulse and a lot of years ago, the maximum data transfer rate of dial-up modems was 56 Kb/s. Broadband technologies, such as DSL and cable modems are used now due to the much higher data transfer rate. Baud rate does not measure the communication speed of those technologies, since they communicate over digital lines.

Is Baud The Same As Bits Per Second Or Bandwidth?

No, baud is not the same as bits per second. Bits per second refers to the maximum number of bits that can be transferred from one place to another in a given period of time and baud refers to the number of signal units that can be transferred per second. Baud rate gives a measure of how much the electronic state changes per second and in modern modems, each state involves more than one bit of data, meaning that it cannot be equal to bits per second.

However, in older modems, bit rate and baud rate are equal because they only use one bit per symbol and each state change is represented as one or zero. If the signal is binary, the baud rate and bit rate are exactly the same.

Also, baud rate is different from bandwidth. Bandwidth is a measure of the number of bits that can be sent or received per second (transmission capacity) and baud refers to the number of signal units that can be transferred per second.

Where Does The Word 'Baud' Come From?

In November 1926, it was defined by the CCITT, now called the ITU. The word ‘baud’ is named after Émile Baudot. He invented the Baudot code for telegraphy. It is written in accordance with the rules for SI units. When it is spelt out (baud), it should start with a lowercase letter, unless it is the first letter of a sentence and the abbreviation (Bd) should always start with a capital letter.