Pool Flow Rate Calculator (GPM)
Calculation Results
*You need a pump capable of moving at least 0 Gallons Per Minute (GPM) to filter your entire pool in 0 hours.
Understanding Pool Flow Rates and Turnover Times
Maintaining a clean swimming pool is about more than just adding chemicals; it requires proper water circulation. The Flow Rate is the measure of how much water your pump moves within a specific timeframe, typically measured in Gallons Per Minute (GPM). This calculator helps you determine the GPM required to achieve proper water sanitation.
What is Turnover Rate?
Turnover rate refers to the amount of time it takes for your pump to circulate the entire volume of water in your pool through the filter system one time. Most health departments and pool professionals recommend a turnover rate of:
- Residential Pools: 8 to 10 hours.
- Commercial Pools: 6 hours or less (often mandated by law).
- Spas/Hot Tubs: 30 minutes to 1 hour.
How to Calculate Required GPM
To find the correct pump size, you must first calculate your pool's volume and then apply the desired turnover time formula:
- Calculate Volume:
Rectangular: Length × Width × Avg Depth × 7.48
Round: π × Radius² × Avg Depth × 7.48 - Calculate GPM:
Formula:Pool Volume (Gallons) ÷ (Turnover Hours × 60)
For example, if you have a 25,000-gallon pool and want an 8-hour turnover:
25,000 ÷ (8 × 60) = 25,000 ÷ 480 = 52 GPM.
Selecting the Right Pump
Once you know your target GPM (e.g., 52 GPM), you should look at pump performance curves. Do not simply buy a pump based on horsepower (HP). A 1 HP pump from one manufacturer may move significantly more water than a 1 HP pump from another, depending on the "Head Pressure" (resistance) of your plumbing system.
Warning: Choosing a pump with a flow rate that is too high for your filter system can damage the filter or reduce filtration quality. Always ensure your filter's maximum designed flow rate exceeds the GPM output of your pump.