FreeHVACCalculators

Heating Cost Calculator

Compare what a million BTU of delivered heat costs from each fuel at your prices — and what a year of heating would cost with each.

Method reviewed October 22, 2026. Version 1.0.0. How it works

Your inputs

Unit system

Million BTU (MMBtu) per year. One way to find it: last year’s gas use in therms × furnace AFUE ÷ 10. Leave the default to compare fuels per MMBtu only.

US residential average: about $1.44/therm (EIA, Feb 2026).

US residential average: $2.69/gal (EIA, Oct 2026, before tax).

US residential average: $6.19/gal (EIA, Oct 2026, before tax).

Seasonal heating efficiency in BTU per watt-hour. Seasonal COP ≈ HSPF2 ÷ 3.412. Real cold-climate performance can be lower.

Result

Natural gas
$606

Natural gas is cheapest at these prices: $15.16 per million BTU, about $606 per year for 40 MMBtu of heat.

Annual heating cost

Natural gas
$606
Propane
$1,238
Heating oil
$2,103
Electric resistance
$2,146
Heat pump
$977

Cost per million BTU of delivered heat

Natural gas
15.16$/MMBtu
Propane
30.96$/MMBtu
Heating oil
52.58$/MMBtu
Electric resistance
53.66$/MMBtu
Heat pump
24.41$/MMBtu
Show the working
  1. Gas: price ÷ (100,000 BTU/therm × AFUE) × 1,000,000
    $1.44 / (100,000 × 0.95) × 10⁶ = $15.16/MMBtu
  2. Propane: price ÷ (91,452 BTU/gal × AFUE)
    $30.96/MMBtu
  3. Oil: price ÷ (138,500 BTU/gal × AFUE)
    $52.58/MMBtu
  4. Electric resistance: price ÷ 3,412 BTU/kWh
    $0.183 / 3,412.14 × 10⁶ = $53.66/MMBtu
  5. Heat pump: price ÷ (HSPF2 × 1,000 BTU/kWh)
    $0.183 / (7.5 × 1,000) × 10⁶ = $24.41/MMBtu

Comparing fuels on equal terms

Fuels are sold in different units — therms, gallons, kilowatt-hours — and burned at different efficiencies. The fair comparison is the cost of one million BTU (MMBtu) of heat actually delivered to the house:

  • Natural gas: price per therm ÷ (100,000 BTU × AFUE).
  • Propane: price per gallon ÷ (91,452 BTU × AFUE).
  • Heating oil: price per gallon ÷ (138,500 BTU × AFUE).
  • Electric resistance: price per kWh ÷ 3,412 BTU.
  • Heat pump: price per kWh ÷ (HSPF2 × 1,000 BTU).

Energy contents are those published by the U.S. Energy Information Administration.

Estimating your annual heat

The annual figure needs the heat your home uses in a year. If you heat with gas now, multiply last winter’s therms by your furnace’s AFUE and divide by 10 to get MMBtu of delivered heat. Otherwise leave the default and use the per-MMBtu comparison, which does not depend on it.

Worked example

These are the example values the calculator opens with, and the result the engine calculates for them.

Inputs

Annual heat needed (delivered)
40
Natural gas price
1.44 $/therm
Gas furnace AFUE
95 %
Propane price
2.69 $/gal
Propane furnace AFUE
95 %
Heating oil price
6.19 $/gal
Oil furnace/boiler AFUE
85 %
Electricity price
0.183 $/kWh
Heat pump HSPF2
7.5

Result

Natural gas is cheapest at these prices: $15.16 per million BTU, about $606 per year for 40 MMBtu of heat.

Assumptions

  • Energy contents: 100,000 BTU per therm of natural gas, 91,452 BTU per gallon of propane, 138,500 BTU per gallon of No. 2 heating oil, 3,412 BTU per kWh.
  • Delivered heat = fuel energy × seasonal efficiency (AFUE for combustion equipment, HSPF2 for heat pumps, 100 % for electric resistance).

Limitations

  • Heat-pump efficiency drops in very cold weather and backup resistance heat may run; HSPF2 is a seasonal rating for a specific climate region and may overstate cold-climate performance.
  • Excludes fixed monthly utility charges, delivery fees, maintenance and equipment cost.
  • Default prices are national averages and will be out of date between updates; enter your own prices.

Frequently asked questions

Is a heat pump cheaper than gas?

It depends on the ratio of your electricity and gas prices and on the heat pump’s real seasonal efficiency. Enter your own prices: where electricity costs less than roughly 2.5–3 times as much as gas per unit of energy, a modern heat pump with a seasonal COP of 2.5–3 usually wins on operating cost.

Why is electric resistance heat so expensive?

Resistance heaters convert one kWh into 3,412 BTU — 100 % efficient, but with no multiplier. A heat pump moves heat from outdoors and typically delivers two to three times as much heat per kWh over a season.

Does HSPF2 reflect cold-climate performance?

Only partly. HSPF2 is a seasonal rating for a reference climate. In very cold regions capacity and efficiency fall and backup heat may run, so real seasonal efficiency can be lower. Cold-climate heat pumps publish performance at 5 °F that helps judge this.

Sources

  1. Energy explained — British thermal units (Btu) — U.S. Energy Information Administration. 100,000 Btu per therm; 1,036 Btu/ft³ natural gas; 91,452 Btu/gal propane; 138,500 Btu/gal heating oil; 3,412 Btu/kWh.
  2. Electric Power Monthly, Table 5.6.A — average price to ultimate customers — U.S. Energy Information Administration. U.S. residential electricity price, 18.31 ¢/kWh in July 2026.
  3. U.S. Price of Natural Gas Delivered to Residential Consumers — U.S. Energy Information Administration. Monthly U.S. residential natural gas prices ($/Mcf).
  4. Heating Oil and Propane Update — U.S. Energy Information Administration. Weekly U.S. residential heating oil and propane prices during the heating season.
  5. What is AFUE? — Carrier. AFUE is the share of fuel energy delivered as heat over a season.
  6. Calculating 5 °F heat pump performance — U.S. DOE. COP = heating output ÷ (3.412 × input watts).

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