Hi,

The most used configuration for serial communication is 8-N-1.

Data bits: 8
Parity: None
Stop bits: 1

This will produce a frame with 10 bits.

Frame:
< 1 start bit >< 8 data bits >< 1 stop bit >

So in order to send one byte with the above configuration you will need 10 bits.
Therefore at 9600 baud you can send 960 bytes per second.

9600 / 10 = 960 bytes per second.

Best regards,

Luciano