The formula
Cost = watts × hours ÷ 1,000 × price per kWh
Everything else is multiplication: × 30.4 for a month, × months open for a season.
Getting a real watts number
This is the input that matters most:
- Variable-speed pumps show watts (or RPM and watts) on the control panel. Use the number at the speed you actually run.
- Single-speed pumps have volts and amps on the motor label. Multiplying them gives “apparent power,” which is a maximum. Typical draw is lower, so the calculator labels that result an upper estimate.
- A clamp meter on the pump circuit, or your utility’s hourly data before and after the pump turns on, measures real use.
The variable-speed comparison
The calculator applies the pump affinity laws: flow is proportional to speed and power to speed cubed. To move the same water at a lower speed, the pump runs proportionally longer. The result shows the theoretical cost at 50%, 66% or 75% speed. ENERGY STAR describes the same principle: half the speed, about one-eighth the power.
Treat it as an upper limit on savings. Real pumps lose some efficiency at low speeds, and some equipment (heaters, salt cells, cleaners) needs higher flow for part of the day.
Electricity rate
The default is about 18¢/kWh, close to the US average residential price in EIA’s 2026 data. State averages range from about 12¢ to over 40¢. For a real answer, divide your bill’s total charges by the kWh used.
Assumptions and limitations
- Volts × amps from the motor label gives an upper estimate; real running power is usually lower.
- Variable-speed savings use the pump affinity laws and are a theoretical upper bound.
- The default rate is a national average from the EIA. Your bill may include fixed charges, tiers or time-of-use pricing that change the real cost.
Key terms
Common questions
How much does it cost to run a pool pump?
Multiply the pump's watts by the hours it runs, divide by 1,000 for kWh, and multiply by your rate. A 1,500 W pump running 8 hours a day uses 12 kWh, about $2.16 a day at 18¢/kWh, or roughly $66 a month.
How much can a variable-speed pump save?
It depends on how you run it. Under the pump affinity laws, half speed uses about one-eighth the power, so moving the same water takes about a quarter of the energy. Real savings are lower because motors, drives and plumbing aren't ideal, but they are often substantial compared with a single-speed pump.
Where do I find my pump's watts?
Variable-speed pumps usually show watts on the display. For single-speed pumps, a clamp meter or the utility's smart-meter data gives real numbers. The nameplate volts × amps is a maximum and overstates typical use.
Sources and methodology references
- ENERGY STAR: Pool pumps, US EPA ENERGY STARHalf speed uses about one-eighth the energy; reduced runtime saves energy.
- Short-Term Energy Outlook: electricity prices, US Energy Information AdministrationAverage US residential electricity price (default rate in this calculator).
- Electric Power Monthly, Table 5.6.A: average price by state, US Energy Information AdministrationFind your state's average residential rate if you don't have your bill.
Published October 2, 2026. Results are estimates. See how our calculators work.
Spotted a wrong result or an outdated source? Report a problem with this calculator.
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