This swimming pool heating cost calculator estimates the energy and cost needed to warm pool water to a target temperature. Enter the pool volume, current and target temperature, heater type, efficiency and your local energy price in USD, GBP, EUR, AUD, CAD or PKR, and it returns a planning estimate for the warm-up and for daily running costs.
CALCULATION GUIDE
This cost to heat a swimming pool calculator estimates the energy needed to raise the water temperature. For a pool measured in US gallons, the approximate heat requirement in British thermal units (BTU) is:
Heat required (BTU) = Pool volume (gallons) × 8.34 × Temperature rise (°F)
To estimate energy use, the calculator converts the heat requirement into energy units and adjusts it for the heater's efficiency or heat-pump coefficient of performance (COP). It then multiplies the estimated energy use by the rate you enter.
- Electric resistance: estimated electricity use is the heat requirement in kWh divided by the heater efficiency.
- Heat pump: estimated electricity use is the heat requirement in kWh divided by the COP.
- Natural gas: estimated therms are based on heat required, heater efficiency and 100,000 BTU per therm.
- Propane: estimated gallons are based on heat required, heater efficiency and an approximate 91,500 BTU per gallon.
Example: estimate the cost to heat a swimming pool
For a 15,000-gallon pool warmed from 70°F to 82°F, the temperature rise is 12°F. The approximate heat requirement is 15,000 × 8.34 × 12 = 1,501,200 BTU, or about 440 kWh of heat. With an electric resistance heater set to 98% efficiency and an example electricity rate of $0.20 per kWh, the estimated electricity use is about 449 kWh and the one-time warm-up cost is about $89.80. Your result will change with your own inputs.
What affects swimming pool heating costs?
Pool volume and temperature rise determine the basic heat requirement. The actual amount of energy used to maintain a temperature can be quite different because heat escapes through evaporation, wind, cool air and the pool structure. A suitable pool cover, local climate, heater condition, run schedule and utility tariff can all affect the final bill.
Swimming pool heating cost calculator UK: using local energy rates
If you are using this swimming pool heating cost calculator in the UK, choose GBP and enter your own electricity rate in pounds per kWh, or your gas rate in pounds per therm. The calculator does not fetch or convert live utility prices. Enter the unit and price exactly as shown on your energy bill.
How much does it cost to heat a pool per month or per day?
The warm-up cost is a one-time figure. The ongoing cost is the heat the pool loses, so it rises with the size of the water surface, wind, cool nights and low humidity, and falls when the pool is covered. Enter the hours your heater runs each day to see a daily running-cost scenario, then multiply by the days in the month. If you only need an occasional swim, heating just before use costs far less than holding the temperature all week.
Warm-up energy for common pool sizes
Energy to warm a pool by 10°F (about 5.6°C), warm-up only| Pool size (US gal) | Heat needed | Heat in kWh | Electric resistance at $0.15/kWh ($) | Heat pump, COP 5, at $0.15/kWh ($) |
|---|
| 10,000 | 834,000 BTU | 244 kWh | 37 | 7 |
| 15,000 | 1,251,000 BTU | 367 kWh | 55 | 11 |
| 20,000 | 1,668,000 BTU | 489 kWh | 73 | 15 |
| 30,000 | 2,502,000 BTU | 733 kWh | 110 | 22 |
Example prices and COP only. The estimate covers the one-time warm-up and ignores heat loss. Enter your own tariff and heater details in the calculator.
Pool heat loss and how long it takes to heat a pool
A pool heat loss calculation needs surface area, wind, humidity and air temperature, and evaporation is normally the biggest loss. This tool does not model weather. It gives the energy to raise the temperature and a running cost for your chosen heater hours, so treat the result as a planning figure and compare it with real bills.
Heat-up time (hours) ≈ Heat required (BTU) ÷ Heater output (BTU/hr)
A 15,000 gallon pool warmed by 10°F needs about 1,251,000 BTU, so a 100,000 BTU/hr heater needs about 12.5 hours at full output before any heat loss. To compare in kilowatts, one kW is about 3,412 BTU per hour, so a 10 kW heater delivers roughly 34,100 BTU/hr. Use the pool heater size calculator to choose output.
Other running costs
This page estimates heating only. For the rest of the monthly bill, see the pool pump electricity cost calculator and the pool water refill calculator, and use the pool volume calculator if you are unsure how many gallons you are heating.
COMMON QUESTIONS
About Swimming Pool Heating Cost Calculator
How much does it cost to heat a swimming pool?
It varies a lot with pool size, climate and heater type. As a simple example, warming 15,000 gallons by 10°F takes about 1.25 million BTU, or roughly 367 kWh of heat. At $0.15 per kWh that is about $55 with an electric resistance heater and far less with a heat pump. This covers the warm-up only, not the heat the pool loses afterwards.
How much does it cost to heat a pool per month?
Monthly cost is mostly the heat the pool loses, not the warm-up. A pool kept at the same temperature all month in a cool or windy climate can cost many times the one-off warm-up figure, while a covered pool in a mild climate costs much less. Enter a realistic daily run time in the calculator to see a running-cost scenario, then compare it with a month of actual energy bills.
What formula can I use to calculate the cost to heat a swimming pool?
First estimate heat in BTU with pool gallons × 8.34 × the temperature rise in °F. Convert that to the energy unit on your bill, adjust for heater efficiency or heat-pump COP, and multiply by your local price per unit. This is a simplified warm-up estimate, not a full prediction of heat loss.
How do I do a pool heat loss calculation?
A full heat loss calculation needs surface area, water and air temperature, wind, humidity and cover use, and evaporation is usually the largest share. This tool does not model weather. It estimates the energy needed to raise the temperature and the cost of running a heater for a number of hours, so use a pool cover and your real bills to judge ongoing losses.
How long will it take to heat my pool?
Divide the heat needed in BTU by the heater's output in BTU per hour. Warming 15,000 gallons by 10°F needs about 1,251,000 BTU, so a 100,000 BTU/hr heater needs about 12.5 hours of full output with no heat loss. Real heat-up takes longer because the pool loses heat as it warms. Enter the rated output in the calculator for an estimate.
How do I convert kW to BTU for a pool heater?
One kilowatt is about 3,412 BTU per hour. A 10 kW electric heater therefore delivers about 34,120 BTU per hour. Pool heater ratings are usually quoted as heat output in BTU/hr or kW, so make sure you compare output with output, not electrical input.
Can I use this swimming pool heating cost calculator for the UK?
Yes. Select GBP and enter your own electricity or gas tariff in pounds, in the unit the calculator shows. The same applies to AUD, EUR, CAD and PKR. The tool does not look up energy prices or convert currencies for you.
Is this a swimming pool cost calculator for building or owning a pool?
No. It estimates heating cost only. For other running costs use the pool pump electricity cost calculator and the pool water refill calculator, which together with heating cover much of a pool's monthly cost.
Will the estimate match my utility bill?
Not exactly. A calculator uses simplified assumptions, while bills include variable rates, fees, weather and real operating patterns. Use the estimate for planning and for comparing heater types.
Can a pool cover reduce heating costs?
A suitable cover reduces heat loss, particularly evaporation, and is one of the most effective ways to lower running cost, though the saving depends on pool use and local conditions.
How do I calculate the cost to heat a swimming pool?
Estimate the heat required for the temperature rise, account for heater efficiency or heat-pump performance, then multiply the energy use by your local tariff. A cost to heat swimming pool calculator does exactly this, using simplified assumptions rather than a full weather model.
How much does it cost to heat a swimming pool each day?
Daily cost depends on how long the heater runs and how much heat the pool loses. Enter an estimated daily run time to see a simple operating-cost scenario, and compare it with your heater's real usage and energy bills over several days.
