Published October 23, 2026 · By RegionalRates
A heater drawing 1,500 watts continuously uses 1.5 kWh in one hour. At an illustrative 16 cents per kWh, that costs $0.24 per operating hour. Your heater's actual setting, thermostat cycling, and electricity rate determine your result.
Calculate your heater's running cost
Read the heater label and manual for its power settings. Use the wattage associated with the setting you are estimating. Enter that value, the hours at that power, days, and your actual rate in the appliance cost calculator.
| Power | 1 hour | 4 hours/day | 4 hours/day for 30 days |
|---|---|---|---|
| 500 W | $0.08 | $0.32 | $9.60 |
| 1,000 W | $0.16 | $0.64 | $19.20 |
| 1,500 W | $0.24 | $0.96 | $28.80 |
These are arithmetic scenarios, not recommended operating schedules or a list of available heater settings. Fixed utility fees are excluded because the table estimates added energy use. Taxes and other variable charges may increase the cost.
What if your electricity costs more?
For the 1,500-watt, four-hour, 30-day scenario, energy use is 180 kWh. That costs $21.60 at 12 cents, $28.80 at 16 cents, or $43.20 at 24 cents per kWh. Replace the example price with the applicable per-kWh components from your bill. Our rate guide shows where to look.
Switched-on time and heating time can differ
If the element cycles, multiplying full wattage by every hour the heater is switched on can overestimate energy use. An illustrative 1,500-watt element active for half of a four-hour period uses 3 kWh, rather than 6 kWh, before accounting for any fan or controls.
Do not assume a 50% duty cycle. Room temperature, drafts, insulation, heater settings, and conditions affect operation. If you do not know the cycle pattern, label the full-power estimate clearly instead of presenting it as a measured result. Our kW versus kWh guide explains the units.
Will a space heater lower the whole-house bill?
Adding a heater without reducing another heating load adds energy use. A room heater could be part of a different heating strategy, but its own cost is only one part of the comparison. You would need to account for the central system's change in consumption, other fuels, comfort needs, weather, and hours of use.
Two resistance heaters with the same actual power draw and operating time consume the same electricity, regardless of their marketing names. Different controls or heat distribution can change how you use them. Do not assume a higher purchase price guarantees a lower electric bill. Heat pumps use a different process; compare the actual systems rather than treating all electric heating as equivalent.
Keep the cost calculation separate from electrical safety
CPSC advises keeping portable heaters at least three feet from combustible materials, plugging electric heaters directly into a wall outlet rather than an extension cord or power strip, and switching them off when sleeping. Follow your heater's instructions as well.
We do not recommend putting an ordinary smart plug or plug-in energy monitor between a portable heater and its wall outlet. A headline amperage rating is not sufficient evidence of compatibility. Use a labeled-wattage estimate or have a qualified professional evaluate an appropriate monitoring method.
If the bill increase seems larger than this estimate
A heater may explain part of a change without explaining all of it. Compare the dates, billing days, rate, and other loads using our high-electric-bill checklist. If your usage data is inconsistent with the estimate, investigate the assumptions rather than simply scaling the claimed savings.
Sources and calculation notes
Safety guidance: CPSC, January 23, 2026. Background on household heating systems: DOE Energy Saver Guide, 2022. Cost examples are RegionalRates calculations using constant rates and stated operating assumptions, not test results.