Pool heating cost calculator

Estimate energy and cost for a pool heating season. Choose a heat pump, natural gas heater or propane heater. Enter the useful heat the pool needs over that season, from an installer assessment or a matching measurement. Useful heat is heat delivered to the water, not electricity or fuel bought by the heater.

For a heat pump, enter assessed seasonal COP. For a fuel heater, enter efficiency as a percentage. These values determine how much purchased energy is needed to deliver your entered heat. Use performance for the water and outdoor conditions in your assessment, rather than an unrelated product test point.

Enter the price in the unit shown for your chosen heater. Electricity uses cents per kWh, natural gas uses dollars per therm and propane uses dollars per US gallon. Propane also requires your supplier's energy content in kWh per US gallon. Changing heater type changes the fields needed.

Purchased heater energy (kWh) = assessed useful seasonal heat ÷ COP for a heat pump, or ÷ fuel efficiency fraction for a fuel heater. Natural gas therms = purchased kWh ÷ fuel energy content in kWh/therm. Propane US gallons = purchased kWh ÷ supplier energy content in kWh/US gallon. Multiply the resulting quantity by its matching price per kWh, therm or US gallon.

COP means heat output divided by electricity input. A COP of 4 supplies 4 kWh of heat for each 1 kWh of electricity, so use the ratio 4 directly. Convert fuel efficiency once: 80% means 0.80. A lower performance value requires more input energy for the same seasonal heat.

The natural gas conversion uses the stored energy per therm. Propane uses your supplied energy content. Electricity prices are divided by 100 to convert cents to dollars; prices already in dollars per therm or gallon need no cents conversion. The working shows purchased energy, fuel units where needed and the matching seasonal cost.

These illustrative inputs are separate from your saved answers. Prices, use and performance are held constant for this worked scenario; they are not personal defaults.

Pool dimensions alone do not establish seasonal heating demand. Weather, cover use, target temperature and operating dates can change the useful heat needed. The calculator does not add a weather model, evaporation allowance or standard heat loss to an empty personal field.

Count initial warm-up once. Include it in the assessed seasonal total, or consider it separately if that assessment leaves it out. Do not add the same heat twice. Keep all inputs for the same pool, season and intended water temperature.

This result covers heater energy only. It excludes circulation pumps, water, chemicals, equipment purchase, repairs and fixed supply charges. It holds the entered prices and performance unchanged. It does not compare financing or calculate installation payback. Personal fields begin empty, and an incomplete edit leaves the last valid result visible with a warning.

The published electricity option uses EIA state residential averages for July 2026, released on 24 September 2026 and checked on 14 October 2026. These describe past average prices. They are not your supplier's offer or a promise of future prices. Choose your bill price for a personal comparison. Include the taxes and usage charges that change with consumption; keep fixed account charges separate.

For gas bills in Ccf or Mcf, use the supplier's conversion to therms before comparing prices. Keep propane quantities in US gallons, not Imperial gallons. Fuel energy content must match the supplier's stated unit and the efficiency basis used for the heater.

Ask a qualified pool heating installer to check seasonal heat demand and performance under the expected conditions. Ask whether the heat assessment includes warm-up and how cover use affects that assessment.

Confirm heater capacity, electrical or gas work and installation requirements before choosing equipment. Take the tariff, fuel information and calculation inputs to the installer. A lower estimated energy cost does not confirm safe installation or that a heater can reach your target temperature in the time available.