You can calculate how much electricity a device or appliance uses with a little bit of research and a stopwatch. The formula is called Watt's Law. Watt's Law defines the relationship between power, current and voltage and is calculated in "watts." Kilowatts per hour, or kilowatt-hours, is the unit your electric bill is measured in. This means that, with some work, you can discover how much electricity your pool pump consumes each time it runs.
Search the instructions or owner's manual for the pool pump to find out the voltage of the motor that powers the pool pump listed in the specifications.
Read the specifications to find out how much current---how many amps, or amperes---the pump uses.
Multiply the amps by the voltage. If the pump uses household current, usually a 110 volt AC (VAC) circuit, at 10 amps, running the pump continuously for one hour requires 1,100 watts of power. Over the course of one hour, that's 1,100 watt-hours, or 1.1 kilowatt-hours (a kilowatt is 1,000 watts).
With a stopwatch, time your pool pump. Record how often it comes on, and how long it stays on each time, over the course of an hour. Total the running time for the hour. If it runs six minutes every hour (0.1 hours), that means it's consuming 1.1 kilowatts of electricity, for 0.1 hours, each hour.
Multiply the power consumption, by the total time of power consumption. The number of kilowatt hours of electricity consumed when the electric pool pump is running equals the electricity times the part of an hour = kilowatt hours consumed per hour. In this case, 1.1 kilowatts x 0.1 hours = 0.11kwh.