To calculate the cost of running the pump you would like to install, use one of the following formulas: WATTS If the pump is rated in watts, use this formula:Pump wattage divided by 1,000 x cost per kilowatt hour x hours in a day x 30.4(billing days each month) = Cost per month to runSo, if I have a pump that uses 300 watts and my electricity costs $0.063/kWh, the formula would look like this:300 / 1,000 x 0.063 x 24 x 30.4 = $13.79 a month to run AMPS If the pump is rated in amps, use this formula:Amps x volts divided by 1,000 x cost per kilowatt hour x hours in a day x 30.4 = Cost per month to runSo, if I have a pump that uses 3 amps and my electricity costs $0.063/kWh, the formula would look like this:3 x 120 / 1,000 x 0.063 x 24 x 30.4 = $16.55 a month to runNot all pumps are created equal. A pump that will move 3,900 gallons in an hour could cost you as little as $8.04/month to run or as much as $45.97/month to run, so shop around and pay close attention to the watts or amps that pump uses. The cheapest pump is not always the best and a pump that costs a little more to buy will save you thousands of dollars over the life of the pump in electrical costs alone.