Pool pump calculator
How hard your pump needs to work, how long it has to run, and what that costs on the electric bill.
In short: Flow needed in gallons per minute = pool gallons ÷ (turnover hours × 60). A 24,000-gallon pool turned over in 8 hours needs 50 GPM. At 50 GPM, one turnover takes 8 hours a day.
Formulas reviewed November 1, 2026 · How we calculate
Using your saved pool: . My pool
31.3 GPM
To filter 15,000 gallons every 8 hours. At 50 GPM your pump does one turnover in 5 hours.
- Run time per day
- 5 hours
- Per month
- 258 kWh
- Per month
- $43.93
What to add
What would change your result
- A variable-speed pump at half speed moves half the water per hour on about an eighth of the power: the same turnover would cost about $10.98 a month instead of $43.93.
- Cloudy water despite long run times usually means a dirty filter, not a weak pump.Read
A variable-speed pump running slower for longer moves the same water with far less power: halving the speed cuts power use to roughly an eighth.
How long to run a pool pump: hours by pool size
Hours for one full turnover at different real pump flows. Most pools aim for one turnover a day.
| Pool size | 30 GPM | 45 GPM | 60 GPM | 80 GPM |
|---|---|---|---|---|
| 10,000 gal | 5.6 h | 3.7 h | 2.8 h | 2.1 h |
| 15,000 gal | 8.3 h | 5.6 h | 4.2 h | 3.1 h |
| 20,000 gal | 11.1 h | 7.4 h | 5.6 h | 4.2 h |
| 25,000 gal | 13.9 h | 9.3 h | 6.9 h | 5.2 h |
| 30,000 gal | 16.7 h | 11.1 h | 8.3 h | 6.3 h |
Getting it right
Turnover is the goal, not hours. Most pools aim to pass all their water through the filter about once a day, in 6 to 10 hours. The calculator turns your pump's flow into that run time.
Use real flow, not the label. A pump rated at 80 GPM may move 45 GPM once pipes, the filter and the heater are in the way. A flow meter or the pump curve at your filter pressure tells the truth.
Run longer in summer. Heat, sun and swimmers use chlorine faster; extra filtration keeps water clear.
Variable speed pays. Power rises with the cube of speed, so running slower for longer moves the same water for a fraction of the electricity.
Key facts
- Most pools are sized for one full turnover of the water in about 8 hours.
- Pump flow drops as filters get dirty and pipes get longer, so use the flow at your system’s resistance, not the maximum on the box.
- Pump power rises with the cube of speed, which is why variable-speed pumps save so much.
How it's calculated
Flow needed = pool gallons ÷ (turnover hours × 60).
Run time = pool gallons ÷ (your pump’s GPM × 60), in hours per turnover.
Monthly energy = watts ÷ 1,000 × run hours × 30.4 days, and the cost is that times your price per kWh.
Questions people ask
How many hours a day should I run my pool pump?
Long enough to turn the water over once, which is pool gallons ÷ (pump GPM × 60). For most pools that is 6 to 10 hours a day, longer in hot weather.
What size pool pump do I need?
One that delivers your pool’s gallons ÷ (8 × 60) GPM at your plumbing’s resistance. A 20,000-gallon pool needs about 42 GPM.
How much does it cost to run a pool pump?
A 1,700 W single-speed pump running 8 hours a day uses about 413 kWh a month, around $70 at 17 cents per kWh.
Is a variable-speed pump worth it?
Usually. Running at half speed uses about an eighth of the power, so the same turnover over more hours costs much less.
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