How Much Does an Electric Heater Cost to Run All Day?
Electric heaters are convenient, but many people wonder how much they actually cost to run, especially if they’re on all day. With electricity prices varying and heaters using different amounts of power, it’s not always obvious whether the cost is minor or something that adds up quickly. Below, we’ll break down how electric heater costs are calculated, look at a few real-world examples, and explain when the cost really matters.
What affects the cost of running an electric heater
The cost of running an electric heater comes down to three main factors:
Heater wattage
Most electric heaters use between 750 and 1,500 watts. Higher wattage means more electricity used per hour.
Electricity rate
Electricity is usually billed per kilowatt-hour (kWh). In many areas, this ranges from $0.15 to $0.30 per kWh, depending on location and utility provider.
How long the heater runs
Running a heater for a few hours a day is very different from running it continuously.
How to calculate the cost
Here’s the simple math:
Watts ÷ 1,000 × hours used × electricity rate = cost
For example:
A 1,500-watt heater uses 1.5 kWh per hour
If electricity costs $0.20 per kWh, that’s $0.30 per hour
Real-world cost examples
Running a 1,500-watt heater for 8 hours
1.5 kWh × 8 hours = 12 kWh
12 kWh × $0.20 = $2.40 per day
That’s about $72 per month if used daily.
Running a 1,500-watt heater all day (24 hours)
1.5 kWh × 24 hours = 36 kWh
36 kWh × $0.20 = $7.20 per day
That’s roughly $216 per month.
Smaller 750-watt heater
A 750-watt heater uses half the electricity:
About $1.20 per day at 8 hours
About $108 per month if run continuously
When the cost really matters
Running an electric heater occasionally or as supplemental heat usually isn’t a big deal. Costs start to matter when:
The heater runs most of the day
Multiple heaters are used at once
Electricity rates are high
The heater is compensating for poor insulation
In these situations, the added cost can become noticeable on a monthly bill.
When the cost is usually minor
The cost is often minimal when:
The heater is used for short periods
It’s heating a small space
It’s used only during the coldest parts of the day
It’s supplementing, not replacing, primary heat
How to estimate your own heater’s cost
To estimate your own cost:
Check the heater’s wattage label
Look up your electricity rate on your utility bill
Multiply by the number of hours you use it each day
For more precise tracking, some people use plug-in power meters to see exact usage.
The bottom line
Electric heaters can be inexpensive for short-term or occasional use, but running one all day can add up over time. The actual cost depends on the heater’s wattage, how long it runs, and local electricity rates. Knowing the math makes it easier to decide whether the cost is minor or worth paying attention to.