Running a 1,500-watt space heater 8 hours a day in Illinois costs about $70.20 a month — $0.29 an hour on full power at Illinois's average 19.23¢/kWh.
At 19.23¢/kWh — Illinois average, Jan–Aug 2026 (EIA). That is 6% above the U.S. average of 18.19¢.
| Period | kWh | Cost |
|---|---|---|
| Per hour of use | 1.5 | $0.29 |
| Per day | 12 | $2.31 |
| Per month | 365 | $70.20 |
| Per season (7 mo) | 2,555 | $491 |
Normal mean temperature (NOAA, population-weighted). Highlighted months average below 60°F.
| Heat source | $ per million Btu | This much heat |
|---|---|---|
| Gas furnace, 95% AFUE | $11.43 | $14.24 |
| Gas furnace, 80% AFUE | $13.58 | $16.91 |
| Propane furnace, 95% AFUE | $22.36 | $27.86 |
| Heat pump (ENERGY STAR avg) | $22.78 | $28.38 |
| Space heater / baseboard | $56.36 | $70.20 |
In Illinois resistance heat costs 4.9× 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 $28.38 a month.
| Heater | Per hour | 8 h/day, month | 24 h/day, month | Season (7 mo, 8 h) |
|---|---|---|---|---|
| 750 W | $0.14 | $35.10 | $105.30 | $246 |
| 900 W | $0.17 | $42.12 | $126.35 | $295 |
| 1,500 W | $0.29 | $70.20 | $210.59 | $491 |
1.5 kW × 8 h = 12 kWh a day; × 30.42 days = 365 kWh a month; × 19.23¢ (Illinois average, Jan–Aug 2026, EIA) = $70.20.
Because resistance heat costs 4.9× as much as gas heat in Illinois, 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 Illinois home used 722 kWh a month in 2025 (EIA); this heater adds 51% to that while it runs.
The full method, material data and tips are on the main space heater cost calculator page.