Heating Cost Calculator

How to use the heating cost calculator

Enter the wattage of the heater, how many hours a day it runs, over how many days, and your electricity rate, and the tool returns what it costs to run. It is the same energy-times-rate arithmetic as any other electric load, framed for space heating because that is where the numbers get large and the misconceptions get expensive.

The rate deserves care here more than anywhere else, since heating multiplies whatever error you make in it. The Energy Information Administration put the US residential average at 18.44 cents per kilowatt-hour in May 2026, with state averages that month running from 12.35 cents in Idaho to 52.00 cents in Hawaii, so take the number off your own bill instead.

Run the per-room arithmetic and space heaters lose their reputation for thrift fast. A 1,500 W heater on eight hours a day for a month is 360 kWh and about $63.00 at $0.175 per kilowatt-hour, and that is one room. Two or three rooms and you are paying more than central heating would have cost to warm the whole house.

Space heaters genuinely win for brief targeted warmth, meaning an hour in the single room you are actually occupying while the rest of the house stays cool, and they lose badly as a whole-home or all-day strategy.

Does a heat pump actually cost less to run?

That 100 percent sounds unbeatable until you meet the heat pump, which does not make heat at all but moves it. Running a refrigeration cycle in reverse, it collects ambient heat from outside and delivers it indoors, so a coefficient of performance of 3 means roughly three units of heat delivered per unit of electricity consumed, and the same warmth costs about a third as much.

That advantage narrows in deep cold, because there is less ambient heat available and many units fall back on built-in resistance strips, so a seasonal average sits below a nameplate figure. If you are heating a space for hours a day across a season, that gap rather than the heater sticker price is where the money is.

The formula, worked line by line

Heating cost is the same energy-times-rate arithmetic as any other electric load, because a resistance heater turns every watt it draws into heat with nothing left over. Watts are divided by 1,000 to become kilowatts, multiplied by the hours a day it runs and by the number of days, and the resulting kilowatt-hours are multiplied by your rate.

Comparing across fuels needs one more step, and it is the step people skip. A therm, a gallon of propane, a gallon of heating oil, and a kilowatt-hour all carry different amounts of energy, and every system converts a different share of that energy into heat you can feel. Divide the price of a unit by its energy content, then divide again by the efficiency, and you get the cost of delivered heat, which is the only figure worth comparing.

kWh = (watts / 1000) x hours per day x days
cost = kWh x rate
heat pump kWh = resistance kWh / COP
cost per MMBtu delivered = price per unit / MMBtu per unit / efficiency

The cross-fuel arithmetic

Here is the cross-fuel calculation behind the table, using electricity at 17.65 cents per kWh. One million Btu is 1,000,000 divided by 3,412, which is 293.1 kWh. At 17.65 cents that is $51.73 of resistance heat, and at a COP of 3 it is $17.24.

Natural gas at $15.06 per thousand cubic feet is $15.06 divided by 1.036 million Btu, which is $14.54 per million Btu of fuel, and a 95 percent furnace turns that into $15.30 of delivered heat. That is why the fuel comparison so often ends the conversation before the heater brand does.

Questions people ask