Firewood for a Winter Calculator
Estimate how many cords of firewood a whole heating season needs from your heat load, hours and wood species.
How it works
season BTU = heat demand × hours/day × days · cords = season BTU ÷ (efficiency × BTU per cord)
Firewood is priced and stacked by the cord — a tightly packed 4 ft × 4 ft × 8 ft pile (128 cubic feet). Multiply your stove’s steady heat output by the hours it burns each day and the length of the season to get the heat you need, then divide by the usable heat in a cord (its raw BTU content times the stove’s efficiency). Denser hardwoods like oak and ash pack far more heat per cord than pine, so species matters as much as price.
Worked example
A 25,000 BTU/hr stove running 12 hours a day for 150 days delivers 25,000 × 12 × 150 = 45 million BTU. At 70% efficiency on oak (24M BTU/cord usable heat is 0.70 × 24M = 16.8M), 45M ÷ 16.8M ≈ 2.7 cords for the season.
Sources: Firewood - Wikipedia
Frequently asked questions
How much is a cord and how do I avoid getting shorted?
A full cord is a stacked 4 × 4 × 8 ft pile = 128 cubic feet. Buy stacked, not thrown loose in a truck bed, and beware "face cords" or "ricks," which are only one row deep (often a third of a cord).
Why does seasoned wood matter so much?
Green wood can be 50% water by weight, and burning off that water steals heat and coats your chimney in creosote. Seasoned wood at 15–20% moisture gives you the BTU numbers above and burns clean.
Is a fireplace as efficient as a stove?
No — an open masonry fireplace is only 10–20% efficient and can even pull more heat up the flue than it delivers. A modern EPA-certified stove or insert reaches 70–80%, so it needs far less wood for the same warmth.
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This calculator is for educational purposes. Double-check important results before acting on them.