Pool & Hot Tub Heating Cost Calculator
Estimate the energy and cost to heat a pool or hot tub by a number of degrees with a gas heater, electric heater or heat pump.
How to use
- 1Enter the water volume and the temperature rise you want.
- 2Choose the heater type and enter its efficiency and your energy prices.
How it's calculated
Energy (BTU) = gallons × 8.34 × temperature rise (°F). Gas: therms = BTU ÷ 100,000 ÷ efficiency. Electric: kWh = BTU ÷ 3,412 ÷ efficiency (COP for heat pumps, often 4–6).
Frequently asked questions
How much does a pool cover save?
Covers can cut heat loss by 50–70%, since most heat escapes through evaporation.
Why is a heat pump cheaper to run?
It moves heat from the air rather than generating it, delivering 4–6 units of heat per unit of electricity in warm weather.
Does this include ongoing heat loss?
No — it's the one-time cost of raising the temperature. Keeping it warm costs more depending on weather and covers.