Transmit/receive power comsuption

According to the datasheet the Xbee series 1 requires 45mA to transmit and 50mA to receive but in this calculations how many bytes or for how long is transmitting/receiving?
If I want to calculate the power comsumption of transmitting 50 bytes, how can I do it from that info?

I would suggest using the battery life calculator located at It will allow you to determine exactly how long it takes to transmit data at any size you tell it.