How Much Does It Cost to Run a Space Heater 24/7?

Running a space heater 24 hours a day can add up quickly, especially if you use a powerful 1,500-watt model. At an electricity rate of $0.18 per kWh in the US, or €0.25 per kWh in Europe, a 1,500-watt heater running continuously would cost about $6.48 (€9.00) per day. That's approximately $194.40 (€270) per 30 days.

However, your actual cost may be lower if the heater's thermostat switches the heating element off periodically. Electricity prices, room insulation, and the temperature you set all affect how much energy you use.

Below, we'll calculate the cost of running different space heaters around the clock and show you how to estimate the expense using your own electricity rate.

The cost depends on your space heater's wattage and your electricity rate. The table below compares three common heater sizes, assuming the heating element runs continuously for 24 hours a day.

If you run a 1,500-watt space heater continuously throughout the year, it would consume 13,140 kWh of electricity.

At the example rates above, that works out to approximately $2,365 per year in the US or €3,285 per year in Europe.

Keep in mind that these figures assume the heater draws its full rated power every hour. In practice, a thermostat may switch the heating element off periodically, reducing electricity consumption. The actual cost will depend on how much heating your room needs and the price you pay for electricity.

You can calculate your space heater's electricity cost using three things: its wattage, how many hours it runs, and your electricity price.

Electricity cost = Heater power (kW) × Hours used × Price per kWh

For example, a 1,500-watt space heater uses 1.5 kilowatts (kW). If it runs continuously for 24 hours, it consumes:

1.5 kW × 24 hours = 36 kWh per day

At an electricity rate of $0.18 per kWh, that costs $6.48 per day. At €0.25 per kWh, it costs €9 per day.

To estimate your monthly cost, multiply the daily cost by 30. If your electricity bill lists a different price per kWh, substitute that rate to get a more accurate estimate.

Your actual electricity bill may be lower or higher than the estimates above. Several factors determine how much energy your space heater uses.

A thermostat can reduce electricity use by switching the heating element off when the room reaches the target temperature. Actual consumption depends on heat loss, outdoor temperature, and the thermostat setting.

Using a suitable energy-saving thermostat can also help you control heating schedules and avoid unnecessary energy use.

A large, poorly insulated room loses heat more quickly than a small, well-insulated one. The heater may therefore need to run more often to maintain the same temperature, increasing energy use.

You can also try these ways to improve your home's energy efficiency without spending money to help reduce heat loss and keep rooms comfortable.

When it's very cold outside, your room loses heat faster. Your space heater may run for longer periods to compensate, increasing your daily electricity costs.

Higher-wattage heaters generally use more electricity when operating at full power. For example, a 1,500-watt heater uses twice as much electricity per hour as a 750-watt heater running continuously.

Your cost per kilowatt-hour (kWh) directly affects your bill. Check your electricity bill for your applicable rate, including any variable energy charges that apply to your consumption. Use that figure in the cost formula above for a more accurate estimate.

Running a space heater continuously can increase fire risk if the appliance is damaged, improperly positioned, or used against the manufacturer's instructions. Although some models have safety features such as overheat protection and tip-over switches, these features do not eliminate every risk.

To use a space heater more safely:

• Follow the manufacturer's instructions. Check whether your model is designed for extended operation, and never bypass its safety features.

• Keep it away from flammable materials. Maintain at least 3 feet (about 1 meter) of clearance from bedding, curtains, furniture, and other combustible items, unless the manual specifies a greater distance.

• Plug it directly into a wall outlet. Avoid extension cords and power strips, which may overheat under heavy electrical loads.

• Place it on a stable, level surface. Keep it away from water and areas where it could be knocked over.

• Avoid leaving it running unattended or while sleeping unless the manufacturer's instructions explicitly permit that use. Switching it off when you leave the room or go to bed is the safer approach.

For European readers, the European Commission's Regulation (EU) 2024/1103 on local space heaters provides an official reference on ecodesign requirements for these appliances. For practical fire-prevention advice, also consult your national or local fire service.

If you rely on a space heater regularly, a few simple changes can help reduce electricity use without sacrificing too much comfort.

• Heat only the room you're using. Keeping one occupied room comfortable can use less energy than heating an entire home, depending on your central heating system and how the rest of the home is heated.

• Lower the thermostat. Setting a comfortable but slightly lower temperature can reduce how often the heater needs to run.

• Improve insulation. Seal drafts around windows and doors, close curtains at night, and use draft excluders to help retain heat.

• Choose an appropriately sized heater. A higher-wattage model isn't automatically more efficient. Match the heater's output to the room and your heating needs.

• Use a timer or thermostat. Schedule heating for when you need it rather than running the heater continuously.

• Compare electricity prices. If your tariff varies by time of day, running the heater during cheaper periods may reduce costs, provided it fits your heating needs. If your electricity tariff changes throughout the day, understanding peak electricity hours may help you identify when electricity costs more and plan your heating accordingly.

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