Heating
Space Heater Electricity Cost Calculator
Estimate how much a portable electric space heater adds to a monthly bill and compare lower heat settings.
How to estimate the cost
Start with the default wattage range of 750 W to 1500 W, then replace it with the value on your appliance label or an energy meter reading. The calculator uses 18.83 cents/kWh as a planning baseline until you enter your own rate.
Scenario comparison
Use the table to test whether wattage or runtime matters more for this appliance before changing settings, replacing equipment, or buying a measurement tool.
| Scenario | Assumption | Monthly use | Monthly cost | Yearly cost |
|---|---|---|---|---|
| Lower-use case | 750 W x 2 hr/day x 30 days
Useful for lower settings, shorter sessions, or better controls. | 45 kWh | $8.47 | $101.68 |
| Default estimate | 1500 W x 4 hr/day x 30 days
Uses the preset shown in the calculator and summary above. | 180 kWh | $33.89 | $406.73 |
| Higher-use case | 1500 W x 6 hr/day x 30 days
Useful for long runtimes, high settings, or seasonal spikes. | 270 kWh | $50.84 | $610.09 |
Space heater cost per hour
At the current default rate of 18.83 cents/kWh, a 1,500 W electric space heater costs about $0.28 per hour while it is actually drawing full power.
| Setting | Watts | Cost per hour | 4-hour evening | 4 hr/day for 30 days |
|---|---|---|---|---|
| Low setting | 750 W
Often closer to a lower heat setting or cycling thermostat behavior. | $0.14 | $0.56 | $16.95 |
| Typical high setting | 1500 W
A common portable space-heater rating in the US. | $0.28 | $1.13 | $33.89 |
| Long high-use hour | 1500 W
Use this when the heater is running continuously on high. | $0.28 | $1.13 | $33.89 |
When the estimate changes the decision
| Situation | Best next check |
|---|---|
| One cold room for a short evening | Estimate cost from watts x hours, then compare it with improving drafts or thermostat settings. |
| Daily use for several hours | Use the calculator with your utility rate and consider measuring kWh if the heater cycles. |
| Using a smart plug or timer | Confirm the device rating and manufacturer instructions before using it with any heater. |
| Replacing whole-home heat | Do not compare a portable resistance heater directly with a heat pump or central system without efficiency context. |
Safety and measurement notes
A plug-in energy monitor can help measure real kWh for a compatible 120 V heater, but the tool must be rated for the load and used according to its manual. Do not use a smart plug, extension cord, or adapter as a workaround when a heater or plug-in device exceeds the rating.
For measurement math, the U.S. Department of Energy explains the watts x hours / 1000 formula and notes that plug-in monitors can measure kWh over time for compatible 120 V devices. For fire-safety context, check the U.S. Consumer Product Safety Commission fire-safety guidance and the heater's own manual.
Sources: DOE Energy Saver appliance energy use and CPSC fire safety information.
What changes the real cost
- Explain that 1500 W is common for high mode in the US.
- Encourage users to enter nameplate wattage instead of relying on defaults.
- Warn that heat pump heating can be much more efficient than resistance heating.
Money-saving angle
Best next checks for this topic: Smart plugs with energy monitoring, safer heaters with thermostats, and home insulation checklists.