Swimming Pool Heating Cost Calculator
Last updated 15 October 2026
Enter a heating task or measured energy to get a heating-cost range.
Your result will appear here
Enter your measurements, then choose Calculate.
Use the expense range to budget the heating task you entered.
Still unknown or unconfirmed
Formula, sources and blank printable worksheet
Initial electricity references: EIA July 2026 and BLS September 2026. These observations define an editable scenario range, not local price bounds. Set both rates to your tariff for a single-rate result.
HEAT-COST-1: useful total Btu = events × (water heat + heat-up loss × hours) + maintenance loss × maintenance hours. Electricity kWh = Btu/(3412.14 × COP/efficiency); therms = Btu/(100000 × efficiency).
Calculation version 1.0 uses historical engineering references for arithmetic, not current residential law.
- Sta-Rite Engineering and Design Manual, second edition, 2003, printed pp. 2, 27, 29, 36-40, 44 https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/manuals/training/Sta-Rite%20Engineering%20and%20Design%20Manual.pdf
- NIST SP811: IT Btu and SI energy conversions https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication811e2008.pdf
- EIA July 2026 residential electricity: 0.1831 USD/kWh; released 24 September 2026 https://www.eia.gov/electricity/monthly/epm_table_grapher.php?t=epmt_es1a
- BLS September 2026 US city electricity via FRED: 0.196 USD/kWh; released 14 October 2026 https://fred.stlouisfed.org/series/APU000072610
- BLS September 2026 US city gas via FRED: 1.700 USD/therm https://fred.stlouisfed.org/series/APU000072620
- EIA July 2026 US residential gas: 26.45 USD/Mcf, released 30 September 2026 https://www.eia.gov/dnav/ng/hist/n3010us3m.htm
- EIA gas conversion: 2025 average 10.37 therms/Mcf; 26.45 / 10.37 = 2.5506 USD/therm https://www.eia.gov/tools/faqs/faq.php?id=45&t=8
| Quantity / unit | Reading | Source and date |
|---|---|---|
| Energy mode | ________________ | ________________ |
| Water volume | ________________ | ________________ |
| Volume unit | ________________ | ________________ |
| Temperature unit | ________________ | ________________ |
| Starting water temperature | ________________ | ________________ |
| Target water temperature | ________________ | ________________ |
| Heat-up hours | ________________ | ________________ |
| Energy conversion | ________________ | ________________ |
| COP (heat pump) or efficiency fraction (gas/resistance) | ________________ | ________________ |
| Source model and air/water/humidity rating conditions | ________________ | ________________ |
| Heat-up event count | ________________ | ________________ |
| Electricity reference low, USD/kWh | ________________ | ________________ |
| Electricity reference high, USD/kWh | ________________ | ________________ |
| Currency label | ________________ | ________________ |
| Gas reference low, USD/therm | ________________ | ________________ |
| Gas reference high, USD/therm | ________________ | ________________ |
Mark missing measurements Unknown. Keep exact model, source revision and assumptions with this worksheet. Report a calculation or source correction with reproducible inputs.
The swimming pool heating cost calculator prices a heat task. You can use a water warm-up or measured energy. It keeps useful heat apart from energy bought. You can edit the dated rates.
For a warm-up, enter water quantity and temperature rise. Add known heat loss for the entered hours. Divide useful Btu by 3,412.14 and efficiency or COP to get electricity kWh. Gas uses 100,000 Btu per therm, then an efficiency adjustment.
Multiply energy by its rate. If loss is unknown, the answer is a lower bound. Measured energy can replace these heat assumptions, but it needs a matching period and rate.
On this page7
Swimming pool heating cost calculator task
Use the capacity calculator to establish useful heat and required output. This tool uses the same water-heat equation: US gallons × 8.33 × positive °F rise. Add constant heat-up loss × heat-up hours for each event. Add maintenance loss × maintenance hours separately.
Do not include the same hours in both loads. A target below the starting temperature gives no water-only warming demand. Maintenance can still need heat, but it is a separate entered task. Unknown weather is not inferred from a postal code.
Heating cost calculator reference rates
The editable electricity rates represent the source periods named here. One is 0.1831 USD/kWh from EIA July home-use data. The other is 0.196 USD/kWh from BLS September US city data. Their methods and periods differ. Neither is a local price limit.
The gas rates use 1.700 USD/therm from BLS September data and about 2.55 USD/therm from EIA July home-use data. To get the latter, divide 26.45 USD/Mcf by 10.37 therms/Mcf. Replace both rates with what you pay for the next unit of fuel. Keep fixed fees and any extra taxes separate. They stay unknown unless entered.
Worked water-only event
For 15,000 US gallons and a 10°F rise, useful heat is 1,249,500 Btu, about 366.19 kWh. At a supplied COP of 5, electrical input is about 73.24 kWh. At an artificial 0.20 currency/kWh, the event costs about 14.65 currency units before losses.
For gas efficiency 0.80, the same useful load needs 15.61875 therms. Use a therm rate for that result. A price per cubic foot cannot be substituted without heat-content conversion. The heating-type comparison explains the different conversion factors.
Measured-use mode
Enter measured electricity kWh or gas therms for the relevant period. The expense is that energy multiplied by the stated rate. Do not add a calculated heat-up load again when it is already included in the measured use.
Keep other loads outside the measurement boundary when comparing heaters. If a meter includes circulation-pump electricity, identify it. This mode does not infer useful heat from a bill total or claim that weather was identical between two measurement periods.
Save the heating scenario
The heat equation is checked against Pentair's engineering reference, printed page 27. The NIST SI guide supplies the IT Btu conversion. Print or download volume, temperatures, losses, rates, efficiency conditions and calculation version 1.0 together.
FAQ
Does the estimate include buying a heater?
No. This tool estimates energy cost for the task. Buying and fitting a heater are separate costs. So are permits and service. Fixed utility fees are separate too. Unknown items stay unknown. A heat result also cannot prove that a model fits your circuit.
Can I use one COP for a whole season?
Only as a stated scenario. A heat pump's COP and output vary with the conditions. One warm-air figure cannot predict a whole season. Use source data that matches each period, or measured input for that period. Note the limits when you hold COP constant in an estimate.
Verdict on heating cost
Use the swimming pool heating cost calculator to compare the same heat load under clear rates and conditions. Read the cost guide when separating maintenance from warm-up. A source-labelled lower bound remains a lower bound after a price is applied.