The short answer
A 200,000 BTU gas pool heater costs about $2.96 an hour to run at U.S. average gas prices, so $355.20 a month at 4 hours a day; on propane, $5.58 an hour. A 100,000 BTU heat pump costs about $0.97 an hour at 18.16¢ per kWh and runs longer, often costing less for the same heat in warm weather.
The same heater in every state
A 200,000 BTU/h natural gas heater, 4 hours a day for 30 days, and warming 20,000 gallons 20°F, at each state's prices.
| Alabama | $405.60 | $68.75 | 16.33¢ |
|---|---|---|---|
| Alaska | $300.00 | $50.85 | 29.41¢ |
| Arizona | $429.60 | $72.82 | 15.05¢ |
| Arkansas | $446.40 | $75.67 | 14.37¢ |
| California | $508.80 | $86.25 | 29.75¢ |
| Colorado | $259.20 | $43.94 | 17.17¢ |
| Connecticut | $388.80 | $65.91 | 24.51¢ |
| Delaware | $369.60 | $62.65 | 18.70¢ |
| District of Columbia | $386.40 | $65.50 | 25.98¢ |
| Florida | $590.40 | $100.08 | 14.99¢ |
| Georgia | $472.80 | $80.15 | 15.90¢ |
| Hawaii | $1,214.40 | $205.86 | 47.18¢ |
| Idaho | $177.60 | $30.11 | 13.37¢ |
| Illinois | $261.60 | $44.34 | 19.32¢ |
| Indiana | $266.40 | $45.16 | 17.02¢ |
| Iowa | $244.80 | $41.50 | 17.06¢ |
| Kansas | $343.20 | $58.18 | 15.47¢ |
| Kentucky | $328.80 | $55.74 | 13.80¢ |
| Louisiana | $403.20 | $68.35 | 12.87¢ |
| Maine | $439.20 | $74.45 | 32.11¢ |
| Maryland | $374.40 | $63.47 | 21.40¢ |
| Massachusetts | $580.80 | $98.45 | 30.48¢ |
| Michigan | $252.00 | $42.72 | 22.99¢ |
| Minnesota | $254.40 | $43.12 | 17.20¢ |
| Mississippi | $386.40 | $65.50 | 14.43¢ |
| Missouri | $345.60 | $58.58 | 16.02¢ |
| Montana | $208.80 | $35.39 | 15.57¢ |
| Nebraska | $264.00 | $44.75 | 13.54¢ |
| Nevada | $304.80 | $51.67 | 12.72¢ |
| New Hampshire | $432.00 | $73.23 | 27.64¢ |
| New Jersey | $328.80 | $55.74 | 24.61¢ |
| New Mexico | $228.00 | $38.65 | 16.51¢ |
| New York | $408.00 | $69.16 | 28.65¢ |
| North Carolina | $379.20 | $64.28 | 14.95¢ |
| North Dakota | $220.80 | $37.43 | 13.31¢ |
| Ohio | $321.60 | $54.52 | 19.38¢ |
| Oklahoma | $333.60 | $56.55 | 14.82¢ |
| Oregon | $386.40 | $65.50 | 15.92¢ |
| Pennsylvania | $348.00 | $58.99 | 21.77¢ |
| Rhode Island | $501.60 | $85.03 | 28.18¢ |
| South Carolina | $391.20 | $66.31 | 15.76¢ |
| South Dakota | $228.00 | $38.65 | 15.15¢ |
| Tennessee | $273.60 | $46.38 | 13.42¢ |
| Texas | $448.80 | $76.08 | 15.91¢ |
| Utah | $235.20 | $39.87 | 13.31¢ |
| Vermont | $417.60 | $70.79 | 23.84¢ |
| Virginia | $388.80 | $65.91 | 17.64¢ |
| Washington | $408.00 | $69.16 | 14.63¢ |
| West Virginia | $319.20 | $54.11 | 16.31¢ |
| Wisconsin | $249.60 | $42.31 | 19.41¢ |
| Wyoming | $271.20 | $45.97 | 14.43¢ |
How it works
The formula
heat pump: kWh an hour = output BTU/h ÷ COP ÷ 3,412
warming = gallons × 8.34 × rise ÷ output (gas output = input × 82%)
Assumptions
- Gas and propane heaters burn their input rating while on; output is 82% of input, the DOE minimum thermal efficiency for gas pool heaters.
- Heat pumps: AHRI Standard 1160 rates them at 80°F air, 63% humidity and 80°F water, where COPs cluster around 5 to 6 (we use 5.5), and at 50°F air, where they fall to about 4. Use your model's rating.
- "Hours a day" is time the heater is firing. Warming the pool ignores heat lost from the surface while it warms, so the real cost is higher on a cool, windy day.
Worked example: a 200,000 BTU gas heater
- 200,000 ÷ 100,000 = 2 therms an hour
- × $1.48 = $2.96 an hour
- × 4 h × 30 days = $355.20 a month
Ways to cut the cost
- Cover the pool overnight and when it's not in use.
- Lower the setting a few degrees; each degree costs heat.
- Run a heat pump in the afternoon, when the air is warmest and its COP is highest.
Questions people ask
How much does it cost to run a pool heater?
A 200,000 BTU gas heater burns 2 therms an hour, about $2.96 at the 2025 U.S. average gas price; 4 hours a day is $355.20 a month. On propane the same heater costs $5.58 an hour. A 100,000 BTU heat pump costs about $0.97 an hour at 18.16¢ per kWh, but runs longer for the same heat.
Is a heat pump or gas pool heater cheaper to run?
Usually the heat pump, per unit of heat: at a COP of 5.5 it delivers 5 to 6 units of heat per unit of electricity on a warm day. It heats slowly and loses efficiency below about 50°F, so gas wins for quick heating and cool nights.
How much does it cost to heat a pool from cold?
Warming 20,000 gallons by 20°F takes 3.3 million BTU: about $60.21 with a 200,000 BTU gas heater (about 20 hours) and $32.28 with a 100,000 BTU heat pump, before heat lost from the surface.
How do I cut pool heating costs?
Use a cover: most of a pool's heat loss is evaporation from the surface. Keep the water a few degrees cooler, and run a heat pump during the warmest hours.