Comparing fuels fairly
Fuels are sold in different units — therms, cubic metres, litres, gallons, kWh — and burned in appliances of different efficiency. Comparing the price per unit tells you very little. The useful number is the cost per kWh of heat delivered into your home, which is what the calculator works out for each option:
Energy contents follow the U.S. Energy Information Administration: heating oil 138,500 Btu per US gallon (about 40.6 kWh, or 10.7 kWh per litre), propane 91,452 Btu per US gallon (about 26.8 kWh, or 7.1 kWh per litre), and natural gas 1,036 Btu per cubic foot. These are gross (higher heating value) figures, consistent with how gas is billed. A heat pump's efficiency is its SCOP × 100%, which is why it can exceed 100%.
Choosing efficiency figures
The efficiency defaults are example assumptions so the comparison works out of the box — replace them with your appliance's figures. In the US and Canada, look for the AFUE rating on furnaces and boilers; in the UK, the ErP or SEDBUK rating. Older non-condensing boilers are typically much less efficient than modern condensing ones, and real-world seasonal efficiency is often a little below the rated figure.
Worked example
A home needs 10,000 kWh of heat a year. Gas at $1.50 per therm in a 95%-efficient furnace costs 1.50 ÷ (29.31 × 0.95) = 5.4¢ per kWh of heat, or about $539 a year. Electric baseboard heaters at 15¢ per kWh cost $1,500. A heat pump with a SCOP of 3 on the same electricity costs 5¢ per kWh of heat — $500 a year.
Reference prices
| Default | Country | Value | Source and period |
|---|---|---|---|
| Natural gas | US | $1.481/therm | U.S. EIA, Natural Gas Prices (annual), 2025 (annual average) |
| Natural gas | UK | 7.97p/kWh | Ofgem, 1 Oct – 31 Dec 2026 |
| Natural gas | Canada | — | No verified national figure on file — the field asks for your own rate. |
| Natural gas | Australia | — | No verified national figure on file — the field asks for your own rate. |
| Heating oil | US | $6.138/gal | U.S. EIA, Heating Oil and Propane Update, week of 12 Oct 2026 |
| Heating oil | UK | — | No verified national figure on file — the field asks for your own rate. |
| Heating oil | Canada | — | No verified national figure on file — the field asks for your own rate. |
| Heating oil | Australia | — | No verified national figure on file — the field asks for your own rate. |
| Propane | US | $2.638/gal | U.S. EIA, Heating Oil and Propane Update, week of 12 Oct 2026 |
| Propane | UK | — | No verified national figure on file — the field asks for your own rate. |
| Propane | Canada | — | No verified national figure on file — the field asks for your own rate. |
| Propane | Australia | — | No verified national figure on file — the field asks for your own rate. |
| Electricity | US | 18.31¢/kWh | U.S. EIA, Electric Power Monthly, Table 5.6.A, July 2026 (preliminary) |
| Electricity | UK | 26.32p/kWh | Ofgem, 1 Oct – 31 Dec 2026 |
| Electricity | Canada | — | No verified national figure on file — the field asks for your own rate. |
| Electricity | Australia | — | No verified national figure on file — the field asks for your own rate. |
Leave a fuel's price blank to drop it from the comparison. The results cover energy only: standing charges, tank rental, deliveries, servicing and installation aren't included. For a closer look at switching to a heat pump, including your gas standing charge, use the Heat Pump Running Cost calculator.
Sources
- U.S. EIA — How do I compare the cost of heating fuels?
- U.S. EIA — British thermal units: heat content of heating oil, propane and natural gas
- U.S. EIA — Heating Oil and Propane Update (weekly residential prices)
- U.S. EIA — Natural gas prices
- Ofgem — Energy price cap unit rates
Results are estimates based on the figures you enter and the stated assumptions. They are not financial, tax, legal or engineering advice. Spotted a problem? Tell us.