How this calculator works
First, work out how much heat the house needs over the winter: the heated area times the annual heat per square foot for your climate, adjusted for insulation, and then the share you want from wood. Then work out how much useful heat one cord of your wood gives, which is its energy content times the efficiency of your stove. Divide one by the other.
Worked example: a 1,800 ft² house in a cold climate (45 kBTU per ft²) with average insulation needs 81 million BTU a year. If wood supplies half (40.5 million BTU) through an EPA-certified stove (70%) burning red oak (24 million BTU per cord), each cord delivers 16.8 million BTU, so you need about 2.4 cords.
Cords for 100% wood heat (EPA stove, red oak, average insulation)
Halve the numbers if wood supplies half your heat.
| Area heated | Mild | Moderate | Cold | Very cold |
|---|---|---|---|---|
| 1000 ft² | 0.9 | 1.8 | 2.7 | 3.6 |
| 1500 ft² | 1.3 | 2.7 | 4.0 | 5.4 |
| 2000 ft² | 1.8 | 3.6 | 5.4 | 7.1 |
| 2500 ft² | 2.2 | 4.5 | 6.7 | 8.9 |
| 3000 ft² | 2.7 | 5.4 | 8.0 | 10.7 |
Tips before you buy
- Hardwoods give about 50% more heat per cord than softwoods, so the type of wood changes the number you need.
- Burn seasoned wood. Wood that is still wet wastes much of its energy boiling off water, and builds creosote in the chimney.
- Efficiency matters as much as the wood. An open fireplace loses most of its heat up the chimney, so it needs several times as much wood as a modern stove for the same warmth.
- Stack off the ground, in a place with wind and sun, with a cover on the top only. Buy at least six months ahead.
- Check how a seller defines a cord: a full cord is 128 ft³ stacked, and a "face cord" is usually a third of that.
Quick answers by size
Tools & materials for this project
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Frequently asked questions
How many cords of firewood do I need for a winter?
Between 2 and 8 cords is typical, depending on the climate, the house and whether wood is your main heat or a supplement. A tight, modern house in a mild area might need half a cord.
How much is a cord of firewood?
A cord is a stack of 128 cubic feet (4 × 4 × 8 ft). Prices vary a lot by region. Use the firewood cord calculator to check a stack or a quote.
How much heat is in a cord of wood?
Roughly 16 to 27 million BTU, depending on the species. Oak and hickory are at the top of the range, and pine and fir at the bottom.
Related calculators & guides
Estimates only. Results assume standard materials and simple shapes. Supplier products vary, and the final call on quantity, structure and safety is yours. Check your local code and your supplier's guidance before ordering.