What does baud mean?
Baud is a unit of signaling speed used in telecommunications, defined as the number of discrete signal events — such as voltage changes or tone shifts — transmitted per second over a communication channel. It takes its name from Jean-Maurice-Émile Baudot, the French engineer whose telegraph system pioneered automated data transmission. The term became familiar to the public during the era of dial-up modems, when connection speeds were commonly quoted in baud. A key point of confusion is that baud does not necessarily equal bits per second: with simple encoding schemes one signal event carries one bit, so the numbers match, but advanced modulation can pack several bits into each signal change, making the bit rate higher than the baud rate. Today the word survives mainly in technical documentation, particularly for serial ports and legacy equipment, where settings like '9,600 baud' remain standard.
nounA unit of signaling speed in data transmission, equal to one discrete signal event (such as a change in state) per second. In modern usage it is largely superseded by bits per second, since each signal event may encode multiple bits.
- A unit of transmission speed equal to one signal event (state change) per second in a communication channel.
"The old modem operated at a blazing 2,400 baud."
"Early telephone modems typically ran at 300 or 1,200 baud."
"The serial link was configured for 9,600 baud, eight data bits, no parity."
In technical writing, the singular form is frequently used attributively after a numeral (e.g. '9600 baud'), though 'bauds' is the standard plural when the unit stands alone.
"The two devices negotiated a connection of 33,600 bauds."
Named after a French engineer who never saw a computer, 'baud' outlived dial-up modems and still confuses people who assume it just means bits per second.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of baud
The word baud derives from the name of Jean-Maurice-Émile Baudot (1845–1903), a French telegraph engineer who invented the Baudot code, an early character-encoding scheme for telegraphy that preceded later binary codes. The unit honoring him was adopted in the field of telecommunications to measure signaling speed. It entered English technical vocabulary in the twentieth century as data transmission developed, becoming widely known with the spread of computer modems.
How baud is actually used
Strictly a technical term used in telecommunications and computing contexts; in everyday speech it appears almost exclusively in discussions of legacy modems and serial-port settings. Because modern modulation schemes encode multiple bits per symbol, 'baud' and 'bits per second' are not interchangeable, though they coincide when one bit is sent per signal event.
Easily confused with baud
A baud measures signal changes per second, while a bit is a unit of information; at high speeds one baud can carry several bits, so the two figures often differ.
Bawd is a noun meaning a person who runs a brothel or procures prostitutes, entirely unrelated to the technical term baud.