How it works
Flueency mathCost per million BTU delivered = price ÷ (heat content per unit × efficiency) × 1,000,000. Season cost = cost per million BTU × the heat you enter.
SourcesHeat contents: EIA (a cord of wood 20,000,000 BTU; propane 91,452 BTU per gallon; natural gas 1,036 BTU per cubic foot; electricity 3,412 BTU per kWh) and the USDA Forest Products Laboratory (premium pellets 16.4 million BTU per ton). Default efficiencies are that laboratory's typical figures, which it notes were developed with boilers in mind, so replace them with your heater's own.
Your pricesThe cordwood, pellet and propane prices filled in are round examples; the natural gas and electricity defaults are EIA US residential averages. Type in your own prices for a real answer.
Common questions
Is wood cheaper than gas?
It depends on your prices. Enter what you pay for a cord and for gas; the calculator compares the heat each delivers, after efficiency.
Why does efficiency matter so much?
A fuel's heat only counts once it reaches the room. A vented gas log set loses most of its heat up the chimney, while a vent-free unit keeps nearly all of it.
Does this include the cost of the heater?
No. It compares fuel only; add the heater, installation and any electricity a pellet stove or blower uses.