Serial Speeds

Note: these table list rates in bits per second. For asynchronous speeds at or below 600 bps and all synchronous speeds listed, this number is also the same as the baud (not "baud rate"). For other speeds, the bits/second figure and the baud may or may not be the same: it depends upon the encoding used to carry the signal.

The term "baud" means "symbols per second" and is already a rate. In normal operations, the "baud rate" should therefore always be zero, thus indicating that signalling is happening at a constant speed. The "baud rate" will be non-zero at the times when signalling is starting, stopping, changing encodings, or changing rates.

Asynchronous Speeds

bits/sec	notes
5 (approx)	professional Morse Code
45.45	WWII era Radio TTY (aka RTTY)
60	Baudot
75	Baudot
110	TTY33; the old standby
134.5	IBM Selectrics
135	same as above
150
200
300	"it's so much faster than 110..."
600

Except for Bell 202A format (the 1200 bps one that no one used much; although it is now used for caller ID signalling), speeds above 600 bps are communicated at 600 baud, with multiple bits per symbol.

bits/sec	notes
1 200	"boy, this is really fast..."
1 800
2 400	the speed modem that every machine came with after 9600 was available...
3 600
4 800
7 200
9 600	"at last, fast enough!"
14 400	but then came...
19 200	2 x 9 600
28 800	fastest base signal rate on a phone line
38 400	4 x 9 600, popular RS-232 and modem speed
56 000	6 x 9 600, popular modem speed
57 600	popular RS-232 speed
115 200	4 x 28 800

Synchronous Speeds

bits/sec	notes
8 000	voice channel sample rate
56 000	US DS0
64 000	European DS0; ISDN B channel
128 000	2 x 64 000; 1/12 T1
144 000	ISDN 2B+D channel
192 000	3 x 64 000; 3/24 T1
230 400	AppleTalk LocalTalk
256 000	4 x 64 000; 1/6 T1, AC-3 stereo
320 000	5 x 64 000; 5/24 T1
384 000	6 x 64 000; 1/4 T1, AC-3 5.1 sound
448 000	7 x 64 000; 7/24 T1
512 000	8 x 64 000; 1/3 T1
576 000	9 x 64 000; 3/8 T1
640 000	10 x 64 000; 5/12 T1
704 000	11 x 64 000; 11/24 T1
768 000	12 x 64 000; 1/2 T1
832 000	13 x 64 000; 13/24 T1
896 000	14 x 64 000; 7/12 T1
960 000	15 x 64 000; 5/8 T1
1 000 000	Corvus Omninet data rate
1 024 000	16 x 64 000; 2/3 T1
1 088 000	17 x 64 000; 17/24 T1
1 152 000	18 x 64 000; 3/4 T1
1 216 000	19 x 64 000; 19/24 T1
1 280 000	20 x 64 000; 5/6 T1
1 344 000	21 x 64 000; 7/8 T1; also 24 x 56 000
1 408 000	22 x 64 000; 11/12 T1
1 411 200	CD data rate (44 100 samples/sec, 16 bits/sample, 2 channels)
1 472 000	23 x 64 000; 23/24 T1
1 536 000	24 x 64 000; T1[*]; IDSN Primary
1 544 000	DS1; T1 + 8 000 bps signaling
1 546 000	unchannelized DS1
2 048 000	E1 (European DS1)
3 000 000	original Ethernet data rate
4 000 000	4 Mbit token ring data rate
4 500 000	60:1 compress components NTSC video
6 176 000	4 x DS1; DS2
10 000 000	Ethernet data rate
12 000 000	USB 1.0 signaling rate
16 000 000	16 Mbit token ring data rate
34 368 000	E3
43 232 000	7 x DS2; 28 x DS1
44 736 000	7 x DS2; 28 x DS1 + overhead; DS3
51 840 000	OC-1 / STS-1
100 000 000	FDDI data rate; FastEthernet
115 000 000	8-bit NTSC video
135 000 000	3 x DS3 + signaling
155 520 000	OC-3 / STS-3
270 000 000	10-bit SDI component video
466 560 000	OC-9 / STS-9
622 080 000	OC-12 / STS-12
800 000 000	FireWire 800 signaling rate
933 120 000	OC-18 / STS-18
1 000 000 000	GigaBitEthernet
1 244 000 000	OC-24 / STS-24
1 866 000 000	OC-36 / STS-36
2 488 000 000	OC-48 / STS-48
4 976 000 000	OC-96 / STS-96
9 953 000 000	OC-192 / STS-192
10 000 000 000	10G Ethernet

[*] "T1" officially refers to the physical hardware used to transport the signal over copper lines. The term "DS1" should be used to refer to the signal itself. People, being people, could care less about such details and the terms "T2" and "T3" have crept into use. But it stops there as the whole system shifts over to the OC/STS naming.