To reverse calculate the baud rate, you perform the equation as such (using 9600bps as the example) -
((16000000 / 9600) / 64) - 1 = 25.04
First divide 16000000 by the desired baud rate (9600) -
16000000 / 9600 = 1666.67
Then divide this answer by 64 -
1666.67 / 64 = 26.04
Then subtract 1 -
26.04 - 1 = 25.04
Since we cannot load SPBRG with anything but a whole number, we must round the result to the nearest 1...which gives us 25. This is going to give us an actual bit rate of -
16000000 / (64(25 + 1)) = 9615.38
This will give us an error percentage of -
((9615.38 - 9600) / 9600) x 100 = 0.16%
This is a more than acceptable error rate for 9600bps.
9600bps is one of those bit rates where you would have to use an odd value crystal speed to get exactly 9600bps with 0% error. This is one of the reasons why lots of microcontrollers use a crystal speed of 11.059MHz.