Do Space Heaters Use a Lot of Electricity?

On this page (8 sections)

1. How much electricity does a space heater use?
2. How do you estimate a heater's electricity cost?
3. How can you measure a space heater's actual electricity use?
4. Does a thermostat reduce electricity use?
5. Is a space heater cheaper than central heat?
6. Do oil-filled radiators use a lot of electricity?
7. How can you use a space heater without wasting electricity?
8. So, do space heaters use a lot of electricity?

Yes, a space heater can use a lot of electricity if it runs for many hours, especially at a high heat setting. Wattage and heating time determine energy use, while your electricity rate determines the energy cost.

A heater used briefly in one occupied room may cost less than heating an entire home for the same period. For a closer estimate, calculate kilowatt-hours from the heater's power and heating time, then apply your utility rate.

How much electricity does a space heater use?

A 1,500-watt heater uses 1.5 kilowatt-hours per hour when running at full power. A 750-watt setting uses 0.75 kilowatt-hours per hour under the same conditions.

To estimate energy use, convert watts to kilowatts by dividing by 1,000, then multiply by the number of hours the heater heats. For example, a 1,500-watt heater heating at full power for 4 hours uses 6 kilowatt-hours.

That estimate assumes the heater draws full power for the entire period. A thermostat may switch heating off and on to maintain the set temperature, so actual consumption can be lower.

Our guide to how many watts a space heater uses explains how to read wattage and compare heat settings.

Do space heaters use a lot of electricity on low?

A low setting generally uses less power while heating than a high setting. Check the heater's manual or label for the wattage of each mode, because “low” doesn't mean the same wattage on every model.

A thermostat can also affect total use by switching heating off when the room reaches its set temperature. A lower setting may take longer to warm a room, so compare energy over the full period you need heat.

How do you estimate a heater's electricity cost?

Multiply kilowatt-hours by your electricity rate per kilowatt-hour. For instance, if a heater uses 1.5 kilowatt-hours in an hour, multiply 1.5 by the rate on your utility bill to estimate that hour's energy charge.

Use your own rate, since electricity costs vary by utility, plan, and location. Some bills also include fixed charges or different rates by time of day, which a basic calculation won't capture.

For a practical estimate:

1. Find the heater's wattage for the setting you use.
2. Divide that number by 1,000 to get kilowatts.
3. Multiply by the hours it heats to estimate kilowatt-hours.
4. Multiply kilowatt-hours by your electricity rate.

The result estimates the energy charge for that heater. See how much it costs to run a space heater for more examples and a fuller calculation.

How can you measure a space heater's actual electricity use?

A plug-in watt meter can measure energy use only when both products' instructions permit the connection and the heater is within the meter's electrical limits. If the heater requires a direct wall connection, estimate its use from wattage and heating time instead.

The Kill A Watt Meter tracks kilowatt-hours and calculates cost forecasts using your electricity rate. Its memory retains accumulated readings when power is interrupted.

The Plug-In Watt Meter displays power, energy, voltage, current, and cost among its 7 display modes. It saves consumption readings when unplugged and has an adjustable overload warning.

An overload warning does not establish that a meter is suitable for a particular heater or provide permission to exceed electrical limits. Check both manuals before connecting anything, and never use a meter to bypass a heater's direct-wall instruction.

For a permitted connection, measure a typical heating period to account for thermostat cycling. Compare the measured kilowatt-hours with your estimate from wattage and hours.

Does a thermostat reduce electricity use?

A thermostat can reduce electricity use by stopping heating at the set temperature. It can reduce the time the heating element runs, though the savings depend on the room, temperature setting, and heating schedule.

The DREO 1500W Thermostat Heater has a built-in temperature sensor and an ECO mode. DREO says this mode adjusts between 1,000 watts and 1,500 watts based on the room temperature.

DREO requires this heater to plug directly into a wall outlet and says not to use an extension cord. Do not connect it through either watt meter or the separate thermostat outlet discussed here.

The DIGITEN Plug-In Thermostat uses a temperature sensor in its remote to control a compatible connected appliance. Its maximum load is 15 amps and 1,800 watts, but that rating alone does not establish heater compatibility.

Use an external thermostat only when the appliance's instructions allow one, and follow both manuals. A thermostat does not make unattended use or unsafe placement safe.

Is a space heater cheaper than central heat?

A space heater may cost less overall when you heat one occupied room instead of the whole home. The result depends on your central system, the room, the heater's power use, and how long each system runs.

Compare the cost for the same period and comfort goal. Don't assume a portable heater is cheaper simply because it warms a smaller area; a high-power heater running for long hours can use substantial electricity.

If you are weighing the options, see whether a space heater is cheaper than central heat. Keep the comparison focused on the rooms you need warm and the hours you use them.

Do oil-filled radiators use a lot of electricity?

Oil-filled radiators can use substantial electricity, with consumption depending on wattage and heating time. The oil stores heat, but it doesn't remove the need to use electricity.

Compare the heater's power setting and the time its heating element runs rather than assuming an oil-filled model automatically costs less. A thermostat may help limit heating time, depending on the room and setting.

Read whether oil-filled radiators use a lot of electricity for details about that heater type. Our best energy-efficient space heaters guide can help you compare features that support more controlled use.

How can you use a space heater without wasting electricity?

Heat the room you occupy, use a suitable thermostat setting, and turn the heater off when you leave. These steps limit unnecessary heating time without relying on a specific heater type.

Keep the heater clear of furniture, curtains, bedding, and other items, and follow its manual's clearance and operating instructions. For more safety guidance, see space heater safety.

So, do space heaters use a lot of electricity?

Space heaters can use a lot of electricity during long periods at high power, while shorter use reduces total consumption. Base your choice on how much space needs heat and how long you need it.

Choose a heater with built-in temperature control if you want it to cycle heating automatically, and estimate costs using your own utility rate. Work through how much it costs to run a space heater before setting your daily heating schedule.

Frequently asked questions

Do space heaters use more electricity than central heat?

They can, but the comparison depends on the central system, how much space you heat, and the hours of use. Heating one occupied room may use less total energy than heating the whole home, but that does not guarantee a lower bill.

Compare energy costs for the same comfort period.

How much electricity does a 1500-watt space heater use?

At full power, a 1500-watt heater uses 1.5 kilowatt-hours for each hour it runs. Actual use can be lower if a thermostat cycles the heater off or a lower setting is selected.

Multiply the kilowatt-hours by your electricity rate to estimate the energy charge.

Does a space heater use electricity when the thermostat is off?

A heater may still draw standby power after its thermostat stops the heating element, depending on the model. Heating energy use falls while the element is off.

Check the manual for standby information, and use a plug-in meter only if both the heater and meter instructions permit that connection.

Are oil-filled radiators cheaper to run than ceramic heaters?

Not just because of the heater type. Running cost depends mostly on how much electricity the heater uses over time, which is shaped by its power setting, thermostat behavior, and hours of operation.

Compare the models' wattage and actual use for the same room and schedule.