Why the pool pump matters
The filter pump is often one of the largest electrical loads in a home with a pool, simply because it runs for many hours every day. Unlike a heater, it runs all season, so a small difference in power or hours adds up over a year. The calculation itself is the same as for any appliance: power in kilowatts times hours times your price per kWh.
Daily kWh = watts × hours ÷ 1,000 (add each speed for variable-speed pumps)
Cost per day = daily kWh × price per kWh
Watts ≈ volts × amps (from the motor label) if watts are not shown
Worked example
- Single-speed pump drawing 1,800 W for 8 hours at $0.17/kWh: 14.4 kWh a day, $2.45 a day, about $74.46 a month or $893.52 a year if it runs every day.
- Variable-speed pump running 2 hours at 1,500 W and 10 hours at 250 W: 3 + 2.5 = 5.5 kWh a day, $0.94 a day, about $28.44 a month or $341.28 a year.
- Saving: $552.25 a year, even though the variable-speed pump runs longer each day.
- Australia: a 1,100 W pump for 6 hours a day at A$0.30/kWh costs about A$60.23 a month. UK: a 750 W pump for 8 hours at £0.25/kWh costs about £45.63 a month.
Why slower is so much cheaper
For centrifugal pumps, the "affinity laws" of pump engineering say that flow is proportional to speed, while power is roughly proportional to the cube of speed. Run a pump at half speed and it moves about half the water but needs only around one-eighth of the power, in theory. Real pumps do not reach the full theoretical saving, but it explains why a variable-speed pump running longer at low speed can filter the same water for a fraction of the energy. Use higher speeds only when needed, for example for vacuuming, a heater, a solar collector, or water features, and check what minimum flow your heater and salt cell require.
Finding your pump's real power
- Motor label: look for watts, or volts × amps. Horsepower is the motor's output, not what it draws from the wall: a "1.5 HP" pump typically draws noticeably more than 1.5 × 746 W.
- Variable-speed pump display: many show live watts at each speed. This is the best figure to use.
- Plug-in or clamp meter: measures actual draw.
How long should the pump run?
The goal is to filter the pool's water often enough to keep it clear and keep sanitiser mixed. Many owners aim to turn the whole volume over about once a day, but the right run time depends on your pump's flow, filter, bather load, debris and climate, and on local rules for public pools. Running at lower speed for longer is usually cheaper than running at high speed for a short time.
Ways to cut pump cost
- Switch to a variable-speed pump and program low speeds for most hours.
- Run filtration at off-peak times if your tariff is cheaper then.
- Keep the filter and skimmer baskets clean: dirty filters raise pressure and reduce flow.
- Use a cover to keep debris out, so you need less filtration.
Common mistakes
- Using horsepower × 746 as the power draw. It underestimates actual watts.
- Forgetting heaters and booster pumps. Add them separately with the electricity cost calculator, and price heating with the pool heating cost calculator.
- Counting 12 months for a seasonal pool. Set the days per year to your swimming season.
Estimates only. Your meter and bill show actual use.
Monthly cost by pump power (8 hours a day)
| Pump draw | US at $0.17/kWh | Australia at A$0.30/kWh | UK at £0.25/kWh |
|---|---|---|---|
| 500 W | $20.68 | A$36.50 | £30.42 |
| 750 W | $31.03 | A$54.75 | £45.63 |
| 1,000 W | $41.37 | A$73.00 | £60.83 |
| 1,500 W | $62.05 | A$109.50 | £91.25 |
| 2,000 W | $82.73 | A$146.00 | £121.67 |
Halve the hours and the cost halves; run at lower watts on a variable-speed pump and the cost falls even further for the same filtration.
Frequently asked questions
How much does it cost to run a pool pump?
Watts × hours ÷ 1,000 × price per kWh. An 1,800 W pump for 8 hours at $0.17/kWh costs about $2.45 a day, or $74 a month.
Does a variable speed pool pump save money?
Usually a lot. In the example, 2 hours at 1,500 W plus 10 hours at 250 W costs $28 a month versus $74 for a single-speed pump at 1,800 W for 8 hours.
How many watts does a pool pump use?
Check the motor label (watts, or volts × amps) or the pump display. Horsepower × 746 underestimates real draw.
Why does running slower save so much energy?
By the pump affinity laws, power rises roughly with the cube of speed: half speed needs around one-eighth of the power in theory.
How much does a 1,000 watt pool pump cost per month?
Running 8 hours a day, about $41 at $0.17/kWh, A$73 at A$0.30/kWh or £61 at £0.25/kWh.
Sources
- US Energy Information Administration: Units and calculators (kWh).
- Pump affinity laws (Hydraulic Institute; standard pump engineering references).
Last reviewed 28 October 2026. Results are estimates; see our disclaimer.