Pool pump energy cost calculator
Enter the power your pump draws at each speed in watts, how many hours a day you run each one, and what you pay for electricity. The calculator returns energy and cost per day, per month, per season and per year, and shows the arithmetic it used.
Result
| Line | Watts | Hours/day | kWh/day | Cost/day |
|---|
Watts, watt-hours and where the money comes from
A watt is a rate: it says how fast the pump is taking energy from the grid at this instant. A watt-hour is a quantity: one watt sustained for one hour. Your utility bills the quantity, in kilowatt-hours, so a pump's wattage alone cannot tell you what it costs. You have to multiply by time.
This is why "pool pump watts per hour" is a phrase worth unpicking: watts are already per unit of time, so "watts per hour" would be a rate of change of power, which is not a thing anyone bills. What you want is either watts (the draw) or watt-hours per day (the consumption).
kWh per day = sum of every speed's kWh, plus standby watts × idle hours ÷ 1000
cost per day = kWh per day × price per kWh
cost per month = cost per day × 30
cost per season = cost per day × season days
cost per year = cost per day × 365
Worked through with the default values: a pump drawing 121 W for 10 hours uses 121 × 10 ÷ 1000 = 1.21 kWh. The same pump at 627 W for 2 hours uses 1.254 kWh. Standby at 3 W for the remaining 12 hours adds 0.036 kWh. That is 2.5 kWh a day, and at 18.31¢ it costs about 46 cents a day, or roughly $82 over a 180-day season.
Assumptions this calculator makes, and the ones it does not
- It assumes constant power at each speed. Real draw drifts as the filter loads up and head rises. A dirty filter raises resistance, which on a variable-speed pump holding a set rpm means more watts.
- It assumes your watts are right. Certified numbers come from a standard test rig, not your plumbing. Measure if the figure matters.
- It does not model savings from slowing down. Halving speed does not halve power — affinity laws put it closer to a cube relationship, which is why variable-speed pumps save what they do. To compare two schedules, run this calculator twice and subtract.
- It does not price the pump, installation or rebates, and it does not know your tariff's time-of-use periods or tiers. If you are on a tiered or time-of-use rate, run it once per period with that period's price and hours.
- It does not decide whether the schedule filters your pool. Hours have to be enough to turn the water over; that is the turnover calculator's job.
Related
Read what the weighted energy factor measures before comparing two pumps on their ratings, browse the certified pump list for the watts of a specific model, or check the methodology for every source behind the defaults above.