Running a 1,500-watt space heater 8 hours a day in Montana costs about $51.58 a month — $0.21 an hour on full power at Montana's average 14.13¢/kWh.
At 14.13¢/kWh — Montana average, Jan–Aug 2026 (EIA). That is 22% below the U.S. average of 18.19¢.
| Period | kWh | Cost |
|---|---|---|
| Per hour of use | 1.5 | $0.21 |
| Per day | 12 | $1.70 |
| Per month | 365 | $51.58 |
| Per season (10 mo) | 3,650 | $516 |
Normal mean temperature (NOAA, population-weighted). Highlighted months average below 60°F.
| Heat source | $ per million Btu | This much heat |
|---|---|---|
| Gas furnace, 95% AFUE | $9.14 | $11.38 |
| Gas furnace, 80% AFUE | $10.85 | $13.51 |
| Heat pump (ENERGY STAR avg) | $16.74 | $20.85 |
| Propane furnace, 95% AFUE | $24.95 | $31.08 |
| Space heater / baseboard | $41.41 | $51.58 |
In Montana resistance heat costs 4.5× as much as gas heat from a 95% furnace. A space heater only saves money when it lets you turn the whole-house thermostat down several degrees and heat just the room you're in. A heat pump delivers the same heat for about $20.85 a month.
| Heater | Per hour | 8 h/day, month | 24 h/day, month | Season (10 mo, 8 h) |
|---|---|---|---|---|
| 750 W | $0.11 | $25.79 | $77.37 | $258 |
| 900 W | $0.13 | $30.95 | $92.84 | $309 |
| 1,500 W | $0.21 | $51.58 | $154.74 | $516 |
1.5 kW × 8 h = 12 kWh a day; × 30.42 days = 365 kWh a month; × 14.13¢ (Montana average, Jan–Aug 2026, EIA) = $51.58.
Because resistance heat costs 4.5× as much as gas heat in Montana, a space heater saves money only if it lets you turn the whole-house thermostat down and heat just the room you're in. If your home heats with electric baseboards or furnace strips, a space heater costs the same per Btu — the saving comes only from heating fewer rooms.
The average Montana home used 853 kWh a month in 2025 (EIA); this heater adds 43% to that while it runs.
The full method, material data and tips are on the main space heater cost calculator page.