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Space Heater Cost Calculator

See what your electric space heater really costs to run. Enter its wattage, how many hours a day you use it and your electricity rate, and get the cost per hour, day, month and heating season, plus how much you save on low or with an eco thermostat setting.

Last updated:

Heater
W

On the label. Most plug-in heaters are 1,500 W on high.

W
%

100% = heating nonstop. With a thermostat the element cycles on and off.

%
Use and price
h

E.g. November to March = 5.

$

On your bill. The US residential average is roughly $0.17/kWh (EIA, 2025).

Enter your values to see the result.
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How to use the Space Heater Cost Calculator

  1. Find the wattage on the heater's label (often 1,500 W high and 750-900 W low).
  2. Enter your use: hours per day, days per month and months in the heating season.
  3. Add your electricity rate per kWh from your bill.
  4. Set the run time: 100% if it heats nonstop, lower if a thermostat cycles it.
  5. Compare settings in the table to see what low or eco mode saves.

Space heater cost formula

Cost per hour = watts ÷ 1000 × run time × price per kWh. Multiply by hours per day for the daily cost, by days per month for the monthly cost and by months of use for the season.

Example: a 1,500 W heater on high, 6 hours a day, 30 days, at $0.17/kWh: 1.5 kWh × $0.17 = $0.255 per hour; × 6 = $1.53 per day; × 30 = $45.90 per month. Over a 5-month winter that is about $230.

Typical space heater running costs

HeaterkWh per hourPer hour at $0.178 h/day for 30 days
400 W personal / desk heater0.4$0.07$16.32
750 W (low setting)0.75$0.13$30.60
1,000 W1.0$0.17$40.80
1,500 W (high setting)1.5$0.26$61.20
1,500 W with thermostat at 50%0.75 avg$0.13$30.60

Electricity prices vary a lot by state and utility, from under $0.12 to over $0.40 per kWh, so use the rate on your own bill (total charges ÷ kWh used gives your all-in rate).

Ways to lower the cost

  • Use a heater with a built-in thermostat or eco mode, and set it to the lowest comfortable temperature.
  • Close the door of the room you are heating and turn the central thermostat down a few degrees.
  • Heat people, not rooms: a small heater near your desk or a heated blanket uses far less power.
  • Use a plug-in timer so the heater is not running in an empty room.
  • Keep 3 ft of clear space around the heater, never leave it running unattended or while sleeping unless it is designed for that, and choose a model with tip-over and overheat shut-off.

Frequently asked questions

How much does it cost to run a 1500 watt space heater?

A 1,500 W heater uses 1.5 kWh per hour on high. At $0.17 per kWh that is about $0.26 per hour, $2.04 for 8 hours, and about $61 a month at 8 hours a day for 30 days. With a thermostat that keeps it heating 60% of the time, it drops to about $37 a month.

How do I calculate space heater cost?

Cost = watts ÷ 1000 × hours × price per kWh. For example, 1,500 W ÷ 1000 × 8 h × $0.17 = $2.04 per day. Multiply by the days you use it for the monthly cost.

Does an eco mode or thermostat really save money?

Yes, if the room reaches the set temperature. A heater with a thermostat switches its element off once the room is warm, so it might only draw full power 40-70% of the time. You pay for the time the element is on, so the saving is roughly proportional to that run time.

Is a space heater cheaper than central heating?

It can be when you heat one small room and turn the central thermostat down for the rest of the house. Electric resistance heat costs more per unit of heat than a gas furnace or heat pump in most areas, so heating a whole home with space heaters is usually more expensive.

Are some space heaters more efficient than others?

All plug-in electric resistance heaters, whether ceramic, oil-filled, infrared or fan types, turn essentially 100% of the electricity into heat. A 1,500 W model of any type makes the same 5,118 BTU per hour. Differences are in how the heat is delivered and how well the thermostat controls run time.

Can I plug a space heater into an extension cord?

No. Heater makers and fire safety groups advise plugging space heaters directly into a wall outlet. A 1,500 W heater draws 12.5 A at 120 V, close to the limit of a 15 A household circuit, and can overheat cords and power strips.

Are all the tools on FreeToolCabin tested for quality and accuracy?

Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.

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