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About this tool
Calculate cords of firewood needed for a heating season by species and stove efficiency, plus stack length and weight.
This calculator works out how many cords of firewood a heating season needs, dividing the heat you must deliver by the heat content of a cord of your chosen species and the efficiency of your stove or fireplace. A full cord is the legal 128 cubic feet — a stack 4 ft high, 4 ft deep and 8 ft long — and species heat values are the published extension-service figures for wood seasoned to 20% moisture, from about 13 MMBtu per cord for cedar to 32.9 for osage orange. It also returns face cords at your log length, seasoned weight, stack length and cost per delivered MMBtu.
Open Firewood Cord Calculator on AltFTool — it loads instantly in your browser.
Enter the values you already know.
Fine-tune the options to match your scenario.
Read the result and use it in your planning or reporting.
A cord of osage orange carries more than twice the heat of a cord of cedar, so the species you burn changes the volume needed dramatically.
An open fireplace delivers around 12% of the wood's heat against 70-80% for a certified stove — a six-fold difference in wood consumed.
Converts between full cords and face cords at your actual log length, which is where most firewood pricing disputes start.
Three to five full cords is typical for a home heated mainly by a certified wood stove in a cold climate. As a worked example, 60 MMBtu of delivered heat from red oak at 24 MMBtu per cord through a 70%-efficient non-catalytic stove needs about 3.6 cords; the same demand through an open fireplace at 12% efficiency would need nearly 21.
A full cord is 128 cubic feet stacked 4 × 4 × 8 ft. A face cord is 4 ft high and 8 ft long but only as deep as the logs are long, so with 16-inch logs it is a third of a full cord and with 24-inch logs it is half. Always confirm the log length before comparing face-cord prices.
Between roughly 2,300 lb for aspen and 5,100 lb for osage orange when seasoned to 20% moisture. Weight tracks heat content almost exactly, because oven-dry wood of every species releases close to the same energy per pound — about 6,400 BTU per pound at 20% moisture.
Osage orange leads at about 32.9 million BTU per cord, followed by shagbark hickory at 27.7 and white oak at 26.4. Softwoods sit far lower — white pine at 15.9 and cedar at 13.0 — so you burn roughly twice the volume for the same heat, though they light easily and are useful for shoulder-season fires.
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