01
The purpose
What does this calculator estimate?
What it costs to heat your pool by fuel type — natural gas, propane, electric, or heat pump.
Heating & Energy · D4
Pool Heating Cost Calculator
What it costs to heat your pool by fuel type — natural gas, propane, electric, or heat pump.
Measure the inputsNatural gas is usually the cheapest fuel where it's available on the street.
Read the full resultPropane costs more per BTU than natural gas — common where no gas line exists.
Check the boundaryElectric resistance is the most expensive way to heat; avoid it for a whole pool.
Useful forHeating & EnergyPlanningComparisonVerification
Live calculation
Heating cost inputs
✓ Checked May 2026
Enter the BTU to deliver, heater type, and rates.
Calculated result
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Enter the required values to calculate.
Enter the known values. Let the engine handle the calculation.
✓ Formula checked↻ Live result○ No account needed
Planning estimate only. Confirm product labels, equipment specifications, qualified-professional advice and local requirements before acting.
The result, explained
Use the Pool Heating Cost Calculator result with context.
What it costs to heat your pool by fuel type — natural gas, propane, electric, or heat pump.
02
The tool
What information does it use?
- Total BTU to deliver: From the heater BTU calculator.
- Heater type: Gas, propane, electric, or heat pump.
- Gas rate: $ per therm (for gas).
- Electric rate: $ per kWh (for electric/heat pump).
- Heater efficiency: AFUE % for gas; ~99% electric resistance.
- Heat pump COP: For heat pumps only.
03
The method
How to use this calculator
- Total BTU to deliverFrom the heater BTU calculator.
- Heater typeGas, propane, electric, or heat pump.
- Gas rate$ per therm (for gas).
- Electric rate$ per kWh (for electric/heat pump).
- Heater efficiencyAFUE % for gas; ~99% electric resistance.
- Heat pump COPFor heat pumps only.
04
The relationship
The formula in plain English
Adjusted BTU = Total BTU ÷ efficiency; then convert to fuel units × rate
1 therm = 100,000 BTU · 1 kWh = 3,412 BTU · propane ≈ 91,502 BTU/gal. Heat pump uses BTU ÷ (COP × 3412).05
Worked through
A worked example: 2,500,000 BTU with an 85% natural gas heater at $1.50/therm
- Adjusted BTU = 2,500,000 ÷ 0.85 = 2,941,176
- Therms = 2,941,176 ÷ 100,000 = 29.4
- Cost = 29.4 × $1.50 = $44.12
| Heater type | Efficiency / COP | Fuel used | Cost* |
|---|---|---|---|
| Natural gas | 85% | 29.4 therms | ~$44 |
| Propane | 85% | 32.1 gal | ~$112 |
| Heat pump | COP 5.0 | 146.6 kWh | ~$21 |
| Electric resistance | 99% | 740 kWh | ~$104 |
06
Why it matters
How the result supports the next decision
Natural gas is usually the cheapest fuel where it's available on the street.
Propane costs more per BTU than natural gas — common where no gas line exists.
07
Good inputs
Improve the estimate before relying on it
- Natural gas is usually the cheapest fuel where it's available on the street.
- Propane costs more per BTU than natural gas — common where no gas line exists.
- Electric resistance is the most expensive way to heat; avoid it for a whole pool.
- Heat pumps beat resistance by their COP — 5× the heat per kWh at COP 5.
- A cover cuts the BTU you must deliver, lowering cost no matter the fuel.
08
The boundary
How to interpret the result
Measurements, equipment specifications, site conditions and local requirements can change the practical result.
The engine reports invalid inputs and safety warnings beside the result. Resolve those messages before using the estimate.
09
Before acting
What should override this estimate?
- Measured site conditions and current test results
- Product labels and manufacturer specifications
- Qualified-professional advice and applicable local codes
10
Common questions
Frequently asked questions
How much does it cost to heat a pool?
It depends on the BTU you need to deliver, your heater's efficiency, and your fuel rate. The calculator divides total BTU by efficiency to get the fuel energy required, then converts to therms, propane gallons, or kilowatt-hours and multiplies by your rate. Heat pumps are handled by their COP rather than a percentage efficiency.
What is the cheapest way to heat a pool?
Where available, natural gas is usually cheapest per BTU, followed closely by a heat pump in a mild climate thanks to its high COP. Propane costs more than natural gas, and electric resistance heating is by far the most expensive. Solar is cheapest of all to run but only works in sunlight.
How do I convert BTU to heating cost?
First divide total BTU by your heater's efficiency to account for losses. Then convert: divide by 100,000 for therms of gas, by 91,502 for gallons of propane, or by 3,412 for kilowatt-hours of electricity. Multiply the result by your local rate for that fuel.
Why does heater efficiency matter for cost?
Efficiency is the fraction of fuel energy that actually ends up in the water. An 85 percent gas heater wastes 15 percent up the flue, so you must buy more fuel than the raw BTU suggests. Dividing by efficiency captures that, which is why a more efficient heater costs less to run for the same heat.
Is a heat pump cheaper to run than gas?
Often yes, in mild climates. A heat pump with a COP of 5 delivers five BTU of heat per BTU of electricity, which can undercut gas per delivered BTU depending on local electricity and gas prices. In cold weather the COP falls and gas may pull ahead for fast heating.
How much does it cost to heat a pool per month?
Anywhere from $50 to $500+ depending on climate, fuel, pool size, and whether you use a cover.
Is it expensive to heat a pool with electricity?
Electric resistance is the priciest method; a heat pump using the same electricity is far cheaper thanks to its COP.
Does a pool cover save heating money?
Yes — covers cut evaporative heat loss dramatically, often halving heating costs.
Primary sources
Use the result with current guidance.
These official references support safe planning context. Product labels, local requirements and qualified-professional advice take priority over a general calculator estimate.