Heating fuel cost comparison calculator
Fuels are sold in gallons, therms, kWh, tons and cords, so their prices can't be compared as they stand. This calculator turns each price into the cost of one million Btu of heat that ends up in the house, after the losses of the furnace, boiler or stove. The example prices are real averages for Maine, with their sources and dates under "Where the numbers come from". Prices change, so every price field is editable: enter what you pay.
This is arithmetic on the prices and efficiencies you enter. It leaves out what a switch would cost (new equipment, installation, a gas hookup, upkeep), and prices move through the winter.
How it's worked out
heat delivered per unit = Btu per unit × efficiency
$ per million Btu = price ÷ heat delivered per unit × 1,000,000
With the example prices, heating oil at $5.97 a gallon in an 87% boiler: 138,500 × 0.87 = 120,495 Btu delivered per gallon, and $5.97 ÷ 120,495 × 1,000,000 = $49.55 per million Btu. A heat pump at $0.26 per kWh and a COP of 3.15: 3,412 × 3.15 = 10,748 Btu per kWh, or $24.19.
For your season, the oil gallons times 138,500 Btu times your oil efficiency gives the heat the house used. Each other fuel's amount is that heat divided by its Btu per unit and its efficiency.
Where the numbers come from
| Fuel | Heat content | Default efficiency | Example price |
|---|---|---|---|
| Heating oil | 138,500 Btu/gal | 87% | $5.97/gal |
| Propane | 91,452 Btu/gal | 93% | $3.46/gal |
| Natural gas | 100,000 Btu/therm | 93% | $1.97/therm |
| Electric resistance | 3,412 Btu/kWh | 100% | $0.26/kWh |
| Heat pump | 3,412 Btu/kWh | COP 3.15 | $0.26/kWh |
| Wood pellets | 16,000,000 Btu/ton | 75% | $357.00/ton |
| Cordwood | 20,000,000 Btu/cord | 73% | $355.00/cord |
- Heat contents for oil, propane, natural gas, electricity and cordwood are the U.S. Energy Information Administration's Btu conversion factors.
- That EIA page has no figure for wood pellets. The 16,000,000 Btu per ton is the value in Efficiency Maine's heating cost calculator. Maine's own weekly heating price tables work out to about 16.5 million Btu per ton.
- A cord of wood varies more than any other fuel here, with species and dryness. EIA uses 20 million Btu, Efficiency Maine 25 million for its firewood row. If you burn dense, well-seasoned hardwood, the higher figure is closer, so try a higher efficiency to see the effect.
- Default efficiencies are Efficiency Maine's (updated September 2026): oil boiler 87%, propane and natural gas boilers 93% (condensing), pellet stove 75%, wood stove 73%, ductless heat pump 315% (COP 3.15). Efficiency Maine also counts losses in pipes and ducts, which I left out to keep one number per fuel. An older non-condensing gas or propane boiler is closer to 80%, and a heat pump in a cold snap runs well below its seasonal COP.
- Example prices: heating oil $5.97 a gallon and propane $3.46 a gallon are the statewide averages (as of October 5, 2026) from the Maine Department of Energy Resources heating fuel prices. Natural gas $1.97 a therm, electricity $0.26 per kWh, wood pellets $357 a ton and cordwood $355 a cord are from Efficiency Maine (September 25, 2026). Prices change, and yours will differ, so change any field to match your bills.
Related
- Oil and propane tank calculator: turn a dip or gauge reading into gallons and estimate when the tank runs low.
- How long will heating oil last: your daily use from two dated readings.
- Cost to fill an oil or propane tank: dollars per delivery by tank size and starting level.
- Heat pump vs oil heating cost: the electricity price where a heat pump matches oil, by COP and oil price.