Flow rate — gallons per minute — can be measured by timing how long the pump takes to move a known volume, or backed out from turnover. It sizes pumps, filters, and runtime.
The example
500 gal moved in 10 minutes.
| A | B | |
|---|---|---|
| 1 | Item | Value |
| 2 | 500 / 10 | — |
| 3 | Flow rate | → 50 GPM |
The formula
The formula:
How it works
How it works:
- Time how long the pump takes to move a known volume (e.g. fill a measured container or drop the level).
- Divide gallons by minutes for GPM.
- Or back out from turnover: GPM = volume ÷ (turnover hours × 60).
- Match GPM to the filter and pump ratings — too high damages the filter.
Educational use only — not chemical-safety or professional advice. Pool chemical dosing varies by product strength, water chemistry, and local rules. Always follow the product label, add chemicals to water (never water to chemical), test before and after, and never mix chemicals. Verify with a professional.
Try it: interactive demo
Gallons moved and minutes.
Variations
GPM from turnover
Back out flow:
Gallons per hour
GPM × 60:
GPM vs filter rating
Within limit?:
Pitfalls & errors
Known volume. Measure accurately — a rough container skews GPM.
Filter limit. GPM above the filter rating damages it.
Zero minutes. No time gives #DIV/0!.
Practice workbook
Frequently asked questions
How do I calculate flow rate in GPM in Excel?
How do I get GPM from turnover?
How do I check GPM against the filter?
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