How do you determine watts for a motor? Is there a formula for calculating watts?

You can figure out watts on a DC power by multiplying volts and amps.

You can figure out watts on a DC motor by multiplying volts and amps. On AC power you can only measure it with a watt meter that is calibrated to measure true RMS watts. Some appliance watt meters on the market only read the power in DC style, but true RMS readings will be lower as they actually measure the power being consumed.