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What Flow Does Your Pool Pump Need?

Reviewed 2026-04

Work out the flow for your pool gallons and chosen turnover time. Take the GPM estimate to an installer, who’ll need your system curve and the model’s curve to choose a pump.

See how the calculations work in our methodology

Already have a pump? See how long to run it each day → Pump Run Time Calculator

Don't know? Estimate gallons with the Volume Calculator →

Confirm your inputs

Before you use a dose, compare every input with your fresh tests and measured pool volume. Confirm each example value only after you’ve checked it. When you change a value, you’ll need to confirm it again.

Shopping for a pump?

Use your gallons and turnover time to estimate flow. To choose a pump model, work through the selection checklist.

Frequently asked questions

Will this calculator tell me which pump to buy?

You’ll get a turnover-flow estimate from your gallons and chosen time. Take it to an installer to select a model and speed for your plumbing and equipment. Keep filtration and sanitation checks separate from the turnover calculation.

What does an installer need to select a pump?

Bring the model’s flow curve at your intended RPM and an assessment of the system’s resistance. Pipework, fittings, filter condition and equipment all affect that resistance. Use suction and discharge measurements to assess operating conditions; a discharge gauge alone is insufficient. Include every device’s minimum and maximum flow.

Can my salt cell or heater change the required flow?

Yes. Your pump’s flow and operating speed must suit every device running on the circuit. Use each manual’s flow limits and operating conditions alongside the turnover estimate when choosing the pump and speed.

Pump Run Time Calculator →Volume Calculator →How to choose a variable-speed pump →

How we calculate this
Your result uses the formulas explained in our methodology. Read the assumptions for your calculation before you use the result.