Pool Heater Sizing Calculator
Size a pool heater based on pool volume, temperature rise, surface area, and wind exposure using BTU calculations.
Inputs
Results
Recommended Heater Size
100,000 BTU/hr
How to Use This Calculator
- Enter your pool volume in gallons — use the Pool Volume Calculator if you don't have this figure.
- Set the current water temperature and your desired temperature in °F to calculate the required heat rise.
- Enter the pool surface area in square feet (length × width for rectangular pools).
- Set wind exposure: 1 = sheltered, 2 = average, 3 = exposed/windy.
- Review Required BTU and Heater Size to select a gas, heat-pump, or solar heater model.
- Check Initial Heat-Up Time and Monthly Operating Cost to compare heater types and plan energy costs.
How the result changes with Current Water Temp
| Current Water Temp | Recommended Heater Size |
|---|---|
| 45 | 200,000 BTU/hr |
| 58 | 150,000 BTU/hr |
| 73 | 100,000 BTU/hr |
| 85 | 100,000 BTU/hr |
What each input means
- Pool Volume
- Total pool water volume in gallons.
- Current Water Temp
- Current pool water temperature.
- Desired Water Temp
- Target water temperature for comfortable swimming.
- Pool Surface Area
- Surface area of the pool (length × width for rectangular).
- Wind Exposure
- 1 = Sheltered, 2 = Average, 3 = Exposed/windy.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersPool Volume = 15000, Current Water Temp = 65, Desired Water Temp = 82, Pool Surface Area = 450 = 5 input(s) provided
- Calculate Recommended Heater SizeRecommended Heater Size100000 = 100000
- Calculate Total BTU RequiredTotal BTU Required2124150 = 2124150
- Calculate Initial Heat-Up TimeInitial Heat-Up Time21.2 = 21.2
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.
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