Disclaimer

What these figures are

Estimates of running cost only, produced by dividing published fuel prices by the efficiency at which each machine converts fuel into delivered heat. The equation, every constant, and every source is on the methodology page, and the computed results are downloadable so the arithmetic can be checked rather than trusted.

What they are not

• Not a quote. Nothing here is an offer, and no figure should be used to hold any installer or supplier to a price.
• Not a survey of your house. The model uses a floor area and a rule-of-thumb heat loss coefficient. It has never seen your insulation, your windows, your ductwork or your air leakage. Only a Manual J load calculation done on site can tell you what your house actually needs.
• Not the total cost of ownership. Equipment price, installation, electrical upgrades, rebates, tax credits, financing, maintenance, expected life, and the fact that a heat pump also replaces an air conditioner are all excluded. A system that costs more to run can be the better purchase once those are counted.
• Not professional advice. Nothing here is engineering, financial, tax or legal advice, and no relationship of professional responsibility is created by reading it.

The specific ways these numbers can be wrong

Listed because a disclaimer that only says "may be inaccurate" tells you nothing useful.

• State averages hide your utility. Two households ten miles apart in this site's own dataset pay $0.097 and $0.193 per kWh. A state mean describes neither.
• Gas standing charges are not modelled. This biases every gas comparison in favour of gas, and the effect grows the better insulated the house is.
• Propane and heating oil are regional, not state, figures. Heating oil is published for two regions only; elsewhere the national number is used.
• The heat loss coefficient is a rule of thumb. It can be wrong by half in either direction, and it is the input that moves the monthly cost most.
• Backup heat is a guess unless you know yours. It is the assumption that moves the verdict most, and the default is a reasonable figure for a well commissioned system rather than a measurement of yours.
• Prices move. The figures are a single heating season's mean and are stated with their date. Fuel prices routinely move more than the margin between two systems.

Where two options land within 10% of each other this site says the comparison is too close to call rather than declaring a winner, because a narrower margin than that is inside the noise.

Errors

This site has published wrong numbers before and will again. When an error is found it is fixed and recorded in the corrections log with the old figure, the new one, and the date. If you think something here is wrong, say so.

External links

Pages here link to the U.S. Energy Information Administration, national laboratories, standards bodies and public forum threads. Those are cited as sources. This site does not control them, is not responsible for their content, and their appearance here is not an endorsement.

No warranty, and the limit of responsibility

This site is provided as is, without warranty of any kind, express or implied, including any warranty of accuracy, completeness, merchantability or fitness for a particular purpose. To the fullest extent permitted by law, no liability is accepted for any loss or damage arising from reliance on anything published here, including any decision to install, not install, replace or keep any heating system.

You are responsible for the decisions you make about your own home. Use these figures to ask better questions of a qualified contractor, not to replace one.

Last reviewed 31 August 2026. See also the terms of use and the privacy notice.