How Much Does a Space Heater Cost to Run?
One formula, a table of real US numbers, and the five changes that actually reduce the bill.
The formula
(Watts ÷ 1,000) × hours × your rate per kWh = cost. A 1,500 watt heater run for 4 hours uses 6 kWh. At $0.17 per kWh that is $1.02. That is the whole calculation — everything else is about how many hours the element is genuinely drawing power.
| Heater | 1 hour | 4 hours/day | 30 days at 4 hrs |
|---|---|---|---|
| 750 W (low setting) | $0.13 | $0.51 | $15.30 |
| 1,000 W | $0.17 | $0.68 | $20.40 |
| 1,500 W (full) | $0.26 | $1.02 | $30.60 |
Calculated at $0.17 per kWh, close to the US residential average. Rates vary widely by state — check your own bill and use the calculator below.
Why your real cost is usually lower
The table assumes the element draws full power the entire time. A thermostat-controlled heater in a closed room does not: it heats to the set temperature, switches the element off, and cycles back on only as the room cools. In a reasonably sealed room that duty cycle is often 40 to 60%, which roughly halves the figures above.
What your state's rate does to the number
US electricity rates range from around $0.11 per kWh in parts of the South and Midwest to well over $0.30 in Hawaii, California and much of the Northeast. That means the same heater can cost twice as much to run in one state as another. Always use your own rate — it is printed on your electricity bill as cents per kWh. Put your rate into the calculator.
Five ways to cut the cost
- Use the timer. Two hours instead of eight is a 75% cut, immediately.
- Turn the central thermostat down. Otherwise you have added a cost rather than replaced one.
- Close the door and block the draft underneath. Free, and it shortens every heating cycle.
- Run on low. A lower setting held longer often uses less than a high setting cycling hard.
- Heat the room you are in, only while you are in it. This is the entire point of zone heating.
Comparing to central heating
The honest comparison is not heater versus furnace, it is one warm room versus a whole warm house. If you are the only person home and you spend the evening in one room, a space heater plus a lower central setting is normally cheaper. With a full house in several rooms at once, central heating wins. More on that in space heater vs central heating.
Common questions
How much does it cost to run a 1500W space heater for 24 hours?
A 1,500 watt heater running continuously for 24 hours uses 36 kWh. At the US average of about $0.17 per kWh that is roughly $6.12 a day. In practice a thermostat-controlled heater cycles off, so real usage is usually far lower.
Is it cheaper to run a space heater or central heating?
Heating one occupied room with a space heater while turning the central thermostat down is usually cheaper. Running a space heater on top of full central heating always costs more.
Do space heaters use a lot of electricity?
They are among the higher-draw appliances in a home — a 1,500 watt heater uses more than a refrigerator, a TV and a laptop combined. The cost is controlled by how many hours it actually draws power, which is what the thermostat and timer are for.
Keep reading
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