20 Mhz
Baud UBRR % of error
300 4166 0.0
600 2082 0.0
1200 1041 0.0
2400 520 0.0
4800 259 0.2
9600 129 0.2
14400 86 0.2
19200 64 0.2
28800 42 0.9
38400 32 1.4
57600 21 1.4
76800 15 1.7
115200 10 1.4

Lady Ada Rants:

Yes, you could always use the datasheet and a calculator. But this sucks so much less.

http://www.wormfood.net/avrbaudcalc.php

Pair it with a AVR fuse calculator and you’ve solved 99% of your problems!