Info Tech Guide

Baud is used to measure the rate of electrical signals, or "signaling elements," for modems, networks, serial cables, and other data transfer mediums.Baud was the prevalent measure for data transmission speed until replaced by a more accurate term, bps (bits per second). 

One baud is one electronic state change per second. Since a single state change can involve more than a single bit of data, the bps unit of measurement has replaced it as a better expression of data transmission speed.

The measure was named after a French engineer, Jean-Maurice-Emile Baudot. It was first used to measure the speed of telegraph transmissions.

At slow speeds, only one bit of information (signaling element) is encoded in each electrical change. The baud, therefore, indicates the number of bits per second that are transmitted. For instance, 300 baud means that 300 bits are transmitted each second (abbreviated 300 bps ). Assuming asynchronous communication, which requires 10 bits per character, this translates to 30 characters per second (cps). For slow rates (below 1,200 baud), you can divide the baud by 10 to see how many characters per second are sent.

At higher speeds, it is possible to encode more than one bit in each electrical change. 4,800 baud may allow 9,600 bits to be sent each second. At high data transfer speeds, therefore, data transmission rates are usually expressed in bits per second (bps) rather than baud. For instance, a 9,600 bps modem may operate at only 2,400 baud.

Some people think that baud and bits per second are equal but the fact is, most modems transmit multiple bits of data per baud, so while the the two values are related, they are typically not equal.