Firewood Cord Calculator
A cord is a measure of stacked air, not wood. One cord is 128 cubic feet of pile — only a fifth of that is actual wood. This converts your pile dimensions and shows what that means for burn time.
Results
Enter your measurements above and press Calculate.
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How this is calculated
A cord is a measure of stacked volume, not of weight or log count. One cord is a stack 4 x 4 x 8 feet, which is 128 cubic feet including the air gaps between splits.
- Stack volume = length x width x height in inches, divided by 12, giving cubic feet
- Cords = cubic feet / 128
- Split count = cubic feet x 14, an empirical figure for hand-split 4 inch firewood packed tightly
- Heat = cubic feet x 15 kBTU, based on seasoned hardwood at roughly 150 kBTU per cubic foot
- Burn time = heat / (stove output in kW x 1,000), assuming the stove runs at rated output throughout
Two assumptions drive the error here. Measurements are of the stack, so how tightly it is packed changes the real wood volume by 20 to 30 percent: thrown wood occupies far more space than stacked wood for the same cord count. The heat figure also assumes hardwood dried to about 20 percent moisture. Green wood or softwood can deliver 30 percent less heat for the same volume, and no stove runs at rated output continuously, so treat burn time as an upper bound rather than an expectation.
Questions people ask
How many cords fit in a pickup truck?
A standard full-size pickup with a 6 foot bed and sides stacked level holds about one third of a cord. A half ton truck with a 8 foot bed holds closer to half. Most sellers deliver by the full cord only.
Is a cord the same as a cubic meter?
No. One cord is 128 cubic feet, which is about 3.6 cubic meters of stacked pile. Because it includes air gaps, a cord is far less energy than 3.6 cubic meters of solid wood.
How long does one cord of firewood last?
On a 20,000 BTU per hour wood stove, a full cord of well-seasoned hardwood burns roughly 20 to 25 days at moderate load. A 40,000 BTU furnace cuts that to about 12 days. Softwood burns about 30 percent faster and gives less heat per cord.
What firewood should I buy?
Hardwood such as oak, maple or beech gives the highest heat per cord and burns longest. Pine and poplar are 20 to 30 percent less efficient, burn hotter and faster, and throw more sparks. Best results come from wood dried to under 20 percent moisture content.
How do I tell if firewood is seasoned?
It should snap cleanly, weigh noticeably less than green wood, and have a bark that has lost its sap sheen. Green wood leaves sticky white residue on the stove glass within a few fires.
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