Pool Pump Runtime Calculator

Pool pump runtime determines how long your pump needs to run each day to circulate and filter all the water in your pool. Running the pump too little leads to algae, cloudy water, and poor chemical distribution. Running it too much wastes electricity.

The Turnover Rule: All pool water should pass through the filter at least once every 8–12 hours. This is called one “turnover.” Most pools need 1–2 turnovers per day depending on conditions.

Turnover Time Formula: Turnover Time (hours) = Pool Volume (gallons) / Pump Flow Rate (GPH) Pump Flow Rate (GPH) = GPM × 60

Pool Volume Calculation:

All measurements in feet. Multiply result by 3.785 for liters.

Common Pool Volumes:

Typical Pump Flow Rates:

• 1.0 HP pump: 50–75 GPM (3,000–4,500 GPH)
• 1.5 HP pump: 60–90 GPM (3,600–5,400 GPH)
• 2.0 HP pump: 70–100 GPM (4,200–6,000 GPH)
• Variable speed (low): 20–40 GPM (1,200–2,400 GPH)
• Variable speed (high): 70–100 GPM (4,200–6,000 GPH)

Seasonal Adjustments: Warmer water grows algae faster and needs more filtration. The season setting on this page picks a turnover figure from the middle of each published band:

There is also a floor of 4 hours a day. A small pool with an oversized pump can clear a full turnover in well under an hour, and the arithmetic would then tell you to run it for 40 minutes, which is not enough for the skimmer to do its job or for chemicals to mix. When the floor is what is setting your answer, the result panel says so rather than quietly overriding the sum.

Variable Speed Pump Savings: A variable speed pump running at half speed uses only about 1/8 the energy, because power goes with the cube of speed. Running a variable speed pump slowly for 12 hours uses far less electricity than a single-speed pump at full tilt for 6 hours, and filters better while it does it.

Energy Cost: A typical 1.5 HP single-speed pump draws about 1.5 kW. A variable speed pump at low speed draws 0.2–0.4 kW. Those are the two defaults this page assumes if you do not type a figure of your own, and the panel always tells you which one it used. Your actual draw is on the motor plate, and it is worth two minutes with a torch to go and read it, because the difference between 1.1 kW and 1.9 kW is most of a hundred dollars a season.

Electricity prices vary enormously by state and country, so the cost lines only appear once you enter your own rate. It is on your bill, usually as a cents-per-kWh figure near the usage total.

Best Time to Run the Pump: Run the pump during off-peak electricity hours when possible, usually overnight or early morning. Always run it during and after chemical treatments so they distribute. If you can only run the pump once a day, late afternoon into early evening is the best window: the sun’s UV has spent the day burning off chlorine, and that is when algae growth peaks.

Use a timer. Clean the skimmer and pump baskets weekly, since a half-blocked basket quietly cuts your real flow rate below the number you typed above. Backwash or clean the filter when pressure rises 8–10 PSI over the clean baseline.