Space Heater vs Oil-Filled Radiator Heater: Which Costs Less to Run?
Fan heaters blast warm air immediately; oil-filled radiators warm slowly and coast after shutoff. People often assume the 'gentler' radiator is cheaper.
Space Heater · per month
$68.58
8 hours/day · 750–1,500 W
Oil-Filled Radiator Heater · per month
$68.58
8 hours/day · 700–1,500 W
Verdict
Identical cost per hour at the same wattage — resistance heat is resistance heat. The radiator's thermal mass can save a little via thermostat cycling and comfort at lower settings, while the fan heater wins for quick bursts in small spaces. Pick by noise and use pattern, not efficiency claims.
Side by side
| Space Heater | Oil-Filled Radiator Heater | |
|---|---|---|
| Typical power | 750–1,500 W | 700–1,500 W |
| Typical usage | 8 hours/day | 8 hours/day |
| Energy per month | 365 kWh | 365 kWh |
| Cost per month (US avg) | $68.58 | $68.58 |
| Cost per year (US avg) | $823 | $823 |
| Cost per month in Hawaii | $170 | $170 |
Rates as of April 2026. Adjust the assumptions on each appliance's page: Space Heater · Oil-Filled Radiator Heater.
Frequently asked questions
Which is cheaper to run: a space heater or a oil-filled radiator heater?
At typical usage and the current U.S. average rate (18.8¢/kWh), the space heater is cheaper: about $68.58/month versus $68.58/month for the oil-filled radiator heater — a difference of 0.0¢ per month.
How much could I save per year by choosing the space heater?
About 0.0¢ per year at typical usage and average rates. In Hawaii (46.6¢/kWh) the annual gap grows to roughly 0.0¢.
Do these numbers apply to my state?
The ratio between the two stays the same everywhere, but the dollar gap scales with your rate — from North Dakota at 12.4¢/kWh to Hawaii at 46.6¢/kWh. Open each appliance's page for the exact cost in your state.