How to work out pool pump running cost
kWh a day = hp × 0.746 ÷ 0.8 × hours (or watts ÷ 1,000 × hours) · cost = kWh × price per kWh
One horsepower is 0.746 kW of output; with about 80 % motor efficiency a 1.5 hp pump draws 1.4 kW. Eight hours a day is 11.2 kWh, 1.68 USD at 0.15 USD per kWh, about 50 USD a month and 300 USD for a six-month season. A 1 hp pump 12 hours a day at 0.20 USD costs 2.24 USD a day.
| Motor | 6 h a day | 8 h a day | 10 h a day | 12 h a day |
|---|---|---|---|---|
| 0.75 hp | 19 USD | 25 USD | 31 USD | 38 USD |
| 1 hp | 25 USD | 34 USD | 42 USD | 50 USD |
| 1.5 hp | 38 USD | 50 USD | 63 USD | 76 USD |
| 2 hp | 50 USD | 67 USD | 84 USD | 101 USD |
Why variable-speed pumps cost less
Pump power falls with the cube of speed. Run at half speed, a pump moves half the water with about one eighth of the power, so it can run twice as long, turn the pool over just the same and use about a quarter of the energy. Since July 19, 2021, the US Department of Energy rule for dedicated-purpose pool pumps means most new inground pumps of about 1 hp and up are variable-speed. To set the hours, use the pool turnover rate calculator; to choose a pump, the pool pump size calculator; for heating costs, the pool heat pump calculator.
Formulas: 1 hp = 0.746 kW, motor efficiency 0.8 assumed for single-speed pumps. The 0.15 USD per kWh default is an example input, not an average: enter the rate on your bill. DOE pool pump rule: Pentair and Jandy DOE guides. Read October 23, 2026.
Frequently asked questions
How much does it cost to run a 1.5 hp pool pump?
A 1.5 hp single-speed pump draws about 1.4 kW. Eight hours a day is 11.2 kWh, which at 0.15 USD per kWh costs 1.68 USD a day, about 50 USD a month. Twelve hours a day costs about 76 USD a month at the same rate.
How do I calculate pool pump kWh?
For a single-speed pump: horsepower × 0.746 ÷ 0.8 (motor efficiency) × hours a day. A 1 hp pump for 12 hours uses about 11.2 kWh. For a variable-speed pump, take the watts on its display, divide by 1,000 and multiply by the hours.
Does a variable-speed pool pump really save money?
Usually yes. Pump power falls with the cube of speed, so at half speed a pump uses about one eighth of the power while moving half the water. Running twice as long at that speed turns the pool over the same and uses about a quarter of the energy.
Is it cheaper to run a pool pump at night?
Only if your utility charges less at night, on a time-of-use plan. On a flat rate the cost per kWh is the same. Running in the day also helps chlorine reach the whole pool while the sun burns it off, so many owners split the run time.
How much does a pool pump add to an electric bill?
Multiply the kWh a day by your rate and the days you run it. A 1.5 hp single-speed pump for 8 hours a day at 0.15 USD per kWh adds about 50 USD a month, or about 300 USD over a six-month season. A variable-speed pump on low can cut that by more than half.