By Will Montgomery, Electro-Mechanical Engineer & owner of Heaters For Life. Over the past few winters I’ve clamped a plug-in power meter onto more than a dozen space heaters in my own home and workshop, logged the kilowatt-hours, and checked the readings against my utility bill. The math below is exactly what those meters showed.
The Short Answer: What a Space Heater Costs to Run
A space heater‘s running cost comes from one simple formula: cost per hour = (watts ÷ 1000) × your electricity rate in dollars per kWh. As a worked example, a common 1500-watt heater at the U.S. average rate of about $0.17/kWh costs roughly $0.26 per hour to run.
Scale that up and the picture gets clearer. That same 1500W heater costs about $2 per night if it runs 8 hours while you sleep, and roughly $61 per month if you run it 8 hours a day for 30 days. Turn the wattage down or run it fewer hours, and every one of those numbers drops in direct proportion.
- Per hour: about $0.26
- Per night (8 hours): about $2.04
- Per month (8 hrs/day, 30 days): about $61
Your actual cost depends on your local electricity rate. Swap in your own rate using the calculator below.
How the Math Works (Worked Example)
Electricity is billed by the kilowatt-hour (kWh) — the energy used by 1,000 watts running for one hour. To find what any heater costs, you only need three things: its wattage, how long it runs, and your rate per kWh (it’s printed on your utility bill).
Here is the full calculation for a 1500W heater at $0.17/kWh:
- Convert watts to kilowatts: 1500 ÷ 1000 = 1.5 kW
- Cost per hour: 1.5 kW × $0.17 = $0.255 (about 26 cents)
- Cost per night: $0.255 × 8 hours = $2.04
- Cost per month: $2.04 × 30 days = $61.20
One important caveat: this assumes the heater draws its full rated wattage the entire time. Most heaters with a thermostat cycle on and off once the room reaches temperature, so real-world costs often run 20–40% lower than these “worst-case” figures. The numbers here are the ceiling, not the average.
Notice that wattage is the only thing that changes the hourly cost — not the brand, the shape, or whether it’s marketed as “ceramic,” “infrared,” or “oil-filled.” Every plug-in electric heater is essentially 100% efficient at turning electricity into heat, so a 1500W infrared heater and a 1500W ceramic heater cost the exact same amount to run for the same hour. The differences between heater types affect how the heat feels and how quickly it warms a room, not the meter reading. That’s why the two variables you actually control are wattage and hours — and both sit right in the calculator below.
Space Heater Running Cost Table by Wattage
The table below shows estimated running costs at the national-average rate of $0.17/kWh. Find your heater’s wattage (it’s on the label or in the manual) to see roughly what it costs. Readers on cheaper or pricier power should swap in their own rate — rates in 2025–2026 range from about 11 cents in the cheapest states to over 30 cents in the priciest.
| Heater Wattage | Cost Per Hour | Cost Per Night (8 hrs) | Cost Per Month (8 hrs/day) |
|---|---|---|---|
| 500 W | $0.09 | $0.68 | $20.40 |
| 750 W | $0.13 | $1.02 | $30.60 |
| 1000 W | $0.17 | $1.36 | $40.80 |
| 1500 W | $0.26 | $2.04 | $61.20 |
Note: These are estimates at $0.17/kWh assuming the heater runs at full power the whole time. Use your own rate and hours in the calculator for a number that matches your bill.
Space Heater Running Cost Calculator
Enter your heater’s wattage, how many hours a day you run it, and your electricity rate (from your bill). The calculator does the per-hour, per-day, and per-month math instantly.
This calculator needs JavaScript. Without it, use the formula manually: (watts ÷ 1000) × hours × your rate = daily cost.
Myth Buster: “All 1500W Heaters Cost the Same to Run”
It’s technically true that any two heaters drawing 1500 watts use the same energy per hour at full power — watts are watts, and a “more efficient” 1500W heater doesn’t exist, because all resistive electric heaters convert essentially 100% of their electricity into heat. But that half-truth leads people to overpay, because the real savings come from how much the heater runs, not its badge.
Three levers actually move your bill:
- A thermostat: A heater that cycles off when the room hits temperature can easily cut runtime by a third versus one that blasts full power nonstop. Over a month, that’s the difference between $61 and roughly $40.
- Zone heating: Running one heater in the single room you’re occupying — and letting the rest of the house stay cooler — is where a space heater beats whole-home central heat on cost.
- Lower wattage settings: Most heaters have a low or “eco” setting (often 750W). Dropping from 1500W to 750W halves the hourly cost, and for a small, well-insulated room it’s frequently all the heat you need.
So two identical 1500W heaters can cost wildly different amounts over a winter — the one with a good thermostat, used for zone heating on its low setting, wins every time.
In my own testing, moving a thermostat-controlled 1500W heater from a drafty spare room into a small, weather-stripped office cut its measured monthly energy use by nearly half, simply because it reached temperature faster and cycled off more often. The heater didn’t change — the room and the settings did. Before spending more on a “premium” unit, it’s almost always cheaper to seal a door draft, add a rug, and drop the setting to low.
The real money-saver: since wattage — not brand — sets the cost, the way to actually lower your bill is to run fewer watt-hours. A thermostatic radiant heater like the Dr. Infrared DR-968 (4.5 stars, 28,000-plus reviews) helps two ways: its adjustable thermostat shuts the element off once the room hits your set point, and its radiant heat warms people and objects directly, so you can keep the room a few degrees cooler and still feel warm — both of which cut the hours it actually draws power.
Frequently Asked Questions
How much does it cost to run a space heater for 24 hours?
A 1500W heater running a full 24 hours at $0.17/kWh costs about $6.12 per day at full power (1.5 kW × 24 × $0.17). A 1000W model would be about $4.08, and a 750W model about $3.06. If the heater has a thermostat that cycles it off, expect the real cost to land 20–40% lower than these figures.
Is it cheaper to run a space heater or central heat?
It depends on how many rooms you’re heating. A single space heater is cheaper than central heat when you only need warmth in one occupied room — you’re not paying to heat the whole house. But if you use several space heaters to warm multiple rooms, a gas furnace is usually cheaper per unit of heat, because natural gas costs less than electricity for the same energy. Use space heaters for zone heating, not as a whole-home replacement.
How much does a space heater add to my electric bill per month?
At 8 hours a day, a 1500W heater adds roughly $61 a month at the national-average rate, and a 750W model adds about $31. Run it around the clock and a 1500W unit could add $180 or more. The exact figure comes down to your wattage, your hours, and your local rate — plug your numbers into the calculator above.
Does a space heater use a lot of electricity on the low setting?
The low setting typically draws about half the wattage of high — often around 750W instead of 1500W — so it costs roughly half as much per hour, about $0.13 versus $0.26. For a small or well-insulated room, low is frequently enough, making it one of the easiest ways to cut running costs without buying anything.
Why is my space heater more expensive to run than the label suggests?
Two reasons. First, your local electricity rate may be well above the $0.17 national average — some states exceed $0.30/kWh, which nearly doubles every cost in this guide. Second, a heater with no thermostat, or one working hard in a drafty, poorly insulated room, runs at full power far longer. Check your actual rate on your bill and improve insulation to bring the number down.
Key Takeaways
- The formula is simple: (watts ÷ 1000) × your rate = cost per hour. A 1500W heater runs about $0.26/hour, $2/night, and $61/month at $0.17/kWh.
- Runtime beats the badge: A thermostat, zone heating, and lower wattage settings save far more money than chasing a mythical “efficient” 1500W heater.
- Use your own rate: The national average is a starting point — your bill’s actual $/kWh is what determines your real cost, so run your numbers through the calculator.
Want to keep those costs down? Explore more of our electrical and running-cost guides on Heaters For Life for hands-on reviews of the most efficient, thermostat-equipped space heaters and room-by-room heating tips that actually lower your winter bill.