Pool Heating Cost Calculator
What does it actually cost to heat a pool where you live? This calculator uses your state's average residential electricity, natural gas, and propane rates to compare all four heater types side by side, no brand bias, no guesswork.
| Heater type | Est. monthly cost |
|---|---|
| Heat pump (COP 5) · cheapest | $176 |
| Natural gas heater (82% eff.) | $631 |
| Electric resistance heater | $879 |
| Propane heater (82% eff.) | $946 |
Estimates use your state's average residential energy rates (2025 EIA annual averages) and a standard uncovered-pool heat-loss factor of 5.5 BTU/hr/ft²/°F. Your utility rate, wind exposure, humidity, and swim schedule will move the real number. A cover cuts costs by roughly 50 to 70 percent because most pool heat loss is evaporation.
How the estimate works
An outdoor pool constantly loses heat, mostly through evaporation at the surface, and your heater's job is to replace that loss. The standard engineering approximation for an uncovered pool is 5.5 BTU per hour per square foot of surface for every degree the water is held above air temperature:
gas cost = BTU / (100,000 x 0.82) x $/therm
heat pump cost = BTU / (3,412 x COP 5) x $/kWh
electric cost = BTU / 3,412 x $/kWh
propane cost = BTU / (91,452 x 0.82) x $/gal
The state rates come from EIA residential averages and are labeled in the result so you can substitute your exact utility rate mentally. Since evaporation drives the loss, the same physics as the evaporation calculator, a cover changes everything: the calculator applies a 65 percent loss reduction when you select one.
Worked example: Florida vs Massachusetts
Same pool, 512 sq ft held 10°F above ambient, uncovered, wildly different bills:
- Florida heat pump: about 2.03 million BTU/month → 119 kWh x 5 COP... roughly $175 per month at 14.8¢/kWh
- Massachusetts heat pump: same BTU, about $375 per month at 31.5¢/kWh
- Florida natural gas: about $630 per month at $2.55/therm
- Massachusetts natural gas: about $555 per month at $2.25/therm
Notice the flip: in Florida the heat pump wins by 3.5x; in Massachusetts gas gets surprisingly close to it. This is exactly why a one-size-fits-all answer to "what does pool heating cost" is useless, the state rates decide the winner.
Three ways to cut the bill
- Cover the pool. 50 to 70 percent savings, pays for itself in weeks. Nothing else comes close.
- Lower the target by 2 degrees. Cost scales linearly with the temperature gap, 2 degrees off an 82°F target is a 20 percent saving in 10-degree-rise conditions.
- Heat on a schedule, not around the clock. Heating only for the weekend from Thursday night costs far less than holding temperature all week, gas heaters especially reward this pattern.
Frequently asked questions
How much does it cost to heat a pool per month?
For a typical 16x32 pool (512 sq ft) held 10 degrees above air temperature with no cover, expect roughly $150 to $400 per month with a heat pump, $300 to $700 with natural gas, and $700 to $1,500 with electric resistance, depending heavily on your state's energy rates and the weather. A cover cuts all of these by 50 to 70 percent.
What is the cheapest way to heat a pool?
For steady season-long heating, a heat pump is cheapest to run in almost every state because it moves 4 to 6 units of heat per unit of electricity. Natural gas wins when you heat occasionally and want fast heat-up, or in states with very cheap gas and expensive power. Solar heaters beat both on running cost (near zero) but need roof space and give up temperature control.
Heat pump vs gas heater: which should I buy?
Heat pumps cost more upfront ($4,000 to $7,000 installed) but run at a quarter to a third of the operating cost; gas heaters are cheaper upfront ($2,500 to $4,500) and heat much faster but burn money in weekly use. Rule of thumb: heat all season on a schedule, buy the heat pump; heat occasionally on demand, buy gas.
How much does a pool cover really save on heating?
Most of a pool's heat leaves through evaporation from the surface. A solar cover used whenever the pool is idle typically cuts heating cost 50 to 70 percent, which for many pools is thousands of dollars per season. It is the single highest-return purchase in pool ownership.
Why is heating so much more expensive in some states?
The physics is the same everywhere; the energy price is not. Electric-resistance heating in Hawaii at 42 cents per kWh costs about four times what it does in North Dakota at 11 cents. Colder ambient air and wind also increase the temperature gap the heater must maintain, which is why shoulder-season heating in the north costs more than mid-summer heating in Florida.