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Pool Heater Operating Cost Calculator
Quick answer: Monthly cost equals heat delivered divided by how efficiently the heater turns fuel into heat, times your price. Gas uses 100,000 BTU per therm and propane about 91,500 BTU per gallon, divided by efficiency; an electric heat pump uses kilowatt-hours equal to heat delivered divided by COP × 3,412.
How it works
Enter the output you need per hour (from the size calculator) and how many hours a month the heater actually fires. The tool converts that heat into therms, gallons or kWh using standard energy contents, then multiplies by the price you pay. COP (coefficient of performance) is heat out divided by electricity in; pool heat pumps often run near 4 to 6 in warm air and lower in cool air, so use a figure for your conditions. Real bills also include pump electricity, which this tool does not count. For the bigger picture, see natural gas vs propane and pool cover heat loss.
Worked example
Figures below are illustrative examples (2026-10-29), not quotes or guarantees.
Assumptions: 100,000 BTU/h delivered, 120 h a month. Natural gas at 84% and $1.40/therm: 12 million BTU ÷ 0.84 ÷ 100,000 ≈ 143 therms ≈ $200. Heat pump at COP 5 and $0.14/kWh: 12,000,000 ÷ 17,060 ≈ 703 kWh ≈ $98.
FAQ
Where do I find my price per therm or kWh?
On your utility bill; include delivery charges for a fair comparison.
How many hours a month does a heater run?
It depends on weather and cover use. A cover often cuts hours more than any equipment change.
Are these my real costs?
No. They are planning estimates; your bill depends on weather, rates and habits.
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