Heater Running Cost Calculator
Free tool
Enter your heater and we'll show the real cost per hour, day, month and season — then price the same heat on every other fuel, so you can see instantly whether you're overpaying.
- 6 fuel types compared
- Uses your own utility rate
- No signup to use it
US average is about $0.17/kWh. Your exact rate is on your utility bill — entering it makes every number below accurate for you.
Advanced: heater efficiency
Electric resistance heaters are 100% — every watt becomes heat. Vented gas units lose heat up the flue (about 80%). Ventless propane and kerosene run near 99%.
1,500W · 8 hrs/day · 7 days a week · $0.17 per kWh
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What this calculator does
It works out what an electric or fuel-burning heater actually costs you to run — per hour, per day, per month and across a full heating season — then prices the same amount of heat on every other fuel so you can see whether you are overpaying.
The formula
- W — heater wattage, from the label or data plate
- t — hours the heater actually runs
- rate — what you pay per kWh, from your utility bill
A 1,500W heater is 1.5 kW. Run it 8 hours at $0.17/kWh and that is 1.5 × 8 × 0.17 = $2.04 a day.
How fuel heaters differ
Gas, propane, diesel, kerosene and pellets are rated in BTU rather than watts, so the calculator converts everything to a common basis before comparing:
One kilowatt equals 3,412 BTU/hr. Propane carries 91,502 BTU per gallon, natural gas 100,000 BTU per therm, kerosene 135,000 and diesel 137,000 per gallon. Efficiency matters too — a vented gas heater loses roughly 20% up the flue, while electric resistance converts 100% of what it draws into heat.
Why the comparison surprises people
Electric heaters are 100% efficient, which sounds unbeatable. But electricity is the most expensive energy per BTU in most of the US, so a cheap plug-in heater often costs more to run than a gas system delivering identical warmth. Efficiency and running cost are not the same thing.
Getting an accurate answer
- Use your real rate — it is on your utility bill and varies widely by state
- Enter the hours the heater actually runs, not the hours it is switched on; a thermostat cycles it off
- Treat the result as a ceiling — most thermostatic heaters draw full power only 60–80% of the time
Quickest saving: heating one room you are actually in, rather than the whole house, usually beats swapping heaters entirely.
Cheapest first. Each row delivers 5,118 BTU/hr — identical warmth, different bills.
| Fuel | Per hour | Per month | Difference |
|---|
Fuel prices are US national averages and move constantly — change the rate above for your area. Estimates for comparison, not a quote.
Get your results plus the winter cost cheat sheet
We'll email the numbers you just calculated, along with the reference sheet we use ourselves.
- Your exact cost per hour, month and season
- All 6 heater fuels ranked by real running cost
- The 5 changes that cut a heating bill fastest
Picked for running cost, not sticker price.
How much does a 1500W heater cost to run?
At the US average of $0.17/kWh, a 1500W heater costs about $0.26 per hour. Run it 8 hours a day, every day, and that is roughly $62 a month or $372 across a six-month heating season. Halve the hours and you halve the bill — wattage and time are the only two things that matter.
Which type of heater is cheapest to run?
Per unit of heat, natural gas is almost always cheapest, followed by diesel, wood pellets, propane, kerosene, then electricity. Electric heaters are 100% efficient, but electricity is the most expensive energy per BTU — which is why a cheap space heater can still cost more to run than a gas system.
Are oil-filled radiators cheaper to run than other electric heaters?
At the same wattage every electric heater costs exactly the same per hour. The saving comes from run time: an oil-filled radiator keeps releasing heat after the element cycles off, so its thermostat calls for power less often over a long session. For short bursts a ceramic fan heater will feel warmer sooner.
Does turning a heater down actually save money?
Yes. A thermostat lowers cost by reducing how long the element runs, not by changing the wattage. Dropping the setting a few degrees, or heating only the room you're in, moves the numbers far more than switching between brands of the same wattage.
Why is my number different from the label?
Labels quote maximum draw. A thermostatic heater cycles, so real consumption is usually 60–80% of the maximum over a long session. Treat this calculator's figure as the worst case, then adjust the hours down to match how much your heater actually runs.
