What does it cost to heat your home?
Enter what you burn now and your prices, compare every fuel instantly.
Prices and efficiency
| Fuel | Price | Efficiency |
|---|---|---|
Natural gasper therm | $ | % |
Propaneper gallon | $ | % |
Heating oilper gallon | $ | % |
Electric heatper kWh | $ | % |
Heat pumpper kWh | $ | % |
Your own prices from your bills — nothing is pre-filled. Efficiency: the AFUE on the label; heat pump = HSPF2 ÷ 3.412.
How do I compare the cost of heating fuels?
Compare the price of the heat, not of the fuel. Divide the price per unit by the heat in that unit and by the efficiency of the heater: a therm of natural gas holds 100,000 BTU, a gallon of propane 91,452, a gallon of heating oil 138,500 and a kilowatt-hour 3,412, by EIA figures. Gas at $1.40 a therm in a 95% furnace costs about $14.74 per million BTU of heat.
How much heat does my home use in a year?
Your bills already tell you. 700 therms of gas burned in a 95% efficient furnace delivered 700 × 100,000 × 0.95 = 66.5 million BTU. The same heat would take about 765 gallons of propane, 565 gallons of heating oil, or 19,500 kWh of electric resistance heat.
Is a heat pump cheaper to run?
Usually far cheaper than electric resistance heat, because it moves heat instead of making it: a heat pump meeting the federal minimum HSPF2 of 7.5 delivers about 2.2 units of heat per unit of electricity over a season. The same 66.5 million BTU takes about 8,900 kWh. Whether it beats gas depends on your local prices — enter them to see.
What efficiency should I enter?
The AFUE on the furnace or boiler label — 80% for an older standard furnace, 95% or more for a condensing one. ENERGY STAR gas furnaces are at least 95%, oil furnaces at least 85%. Electric baseboard is 100%; for a heat pump, divide its HSPF2 by 3.412 and multiply by 100.
Where do I find fuel prices?
On your latest bills — divide the total by the therms, gallons or kWh — or from your utility and local fuel dealers. Include delivery and fixed charges only if they would change with the switch.
Does this include the cost of new equipment?
No, it compares running costs only. To judge a switch, divide the extra price of the new equipment (after any incentives) by the yearly saving from the table: that gives the simple payback in years. A system that costs less to run can still take a long time to pay for itself.
My gas bill is in CCF, not therms. What do I enter?
A CCF is 100 cubic feet of gas. Your bill normally shows a therm factor for the month (the heat content per CCF); multiply the CCF by it to get therms, or divide the dollar amount by the therms. If your bill shows only dollars and CCF, use the dollars per therm from the bill's usage summary.
How the comparison works
The calculator first finds the heat your home actually received in a year: fuel used × heat content per unit × efficiency of the equipment. It then asks how much of each other fuel would give the same heat at that fuel's efficiency, and multiplies by the price you enter. The price of a million BTU of delivered heat is price ÷ (BTU per unit × efficiency) × 1,000,000, which is the figure to compare between fuels.
Worked example
Take 700 therms of natural gas burned in a 95% furnace: 66.5 million BTU of heat. The same heat takes 765 gallons of propane at 95%, 565 gallons of heating oil at 85%, 19,490 kWh of electric resistance heat at 100%, or 8,859 kWh with a heat pump at 220%.
With example prices of $1.40 a therm, $2.50 a gallon of propane, $3.50 a gallon of oil and $0.16 a kWh, which are made up for the illustration and not market prices, the yearly costs are about $980 for gas, $1,914 for propane, $1,977 for oil, $3,118 for resistance heat and $1,417 for the heat pump. Change the prices and the order changes, which is why the calculator takes only your prices.
Mistakes to avoid
Comparing the price per unit of fuel is the main one: a gallon of propane, a gallon of oil and a therm of gas do not hold the same energy. Using the efficiency of a new furnace for an old one is another, and so is using a heat pump's best-case figure for a cold climate: the 220% here is a seasonal average at the federal minimum rating (HSPF2 7.5), and a heat pump delivers less heat per kWh on the coldest days. Check each unit on the bill (therms, CCF, gallons, kWh) before dividing, and include only the charges that would change if you switched fuel.
Sources: heat content per unit of fuel from the US Energy Information Administration (EIA); ENERGY STAR efficiency thresholds for gas and oil furnaces; the federal minimum HSPF2 of 7.5 for heat pumps (US Department of Energy). The prices in the example are for illustration only. Related tools: heat loss, furnace size and BTU calculators.