Firewood calculator
How many cords will you burn this winter?
Your state's NOAA heating degree days, your floor area and house age give the heat; the wood species and stove give the cords.
- 1Species 52 from 2 extension tables
- 2States 48 NOAA normals
- 3Stoves 20 maker ratings
- 4Sizes 3 floor-area bands
Fine-tune: wood, stove and price
Stoves that fit
How the answer is worked out
Climate. Each state's heating degree days are the 1991-2020 average of NOAA's statewide annual totals (base 65°F). Heat the house needs. The federal Residential Energy Consumption Survey measured how much gas heated homes burned per 1,000 sq ft per degree day, by the decade they were built: 4.688 cubic feet for homes built since 1990, up to 8.784 for homes built before 1950. Cord Calc multiplies that by your floor area and your state's degree days, converts the gas to Btu (1,036 per cubic foot, EIA) and takes the 78% that a furnace built to the federal minimum turns into heat. Cords. That heat, divided by the energy in a cord of your wood and by the stove's efficiency, is the woodpile. The default stove efficiency, 74%, is the median of the 13 higher-heating-value figures published by the stove makers listed here.
Stove size. The house's average heat loss per degree, taken from the same estimate, gives the heat needed on your coldest night; the stoves listed are the ones whose makers rate them for your floor area, flagged if their published output falls short. Everything is an estimate from averages: a drafty house, a closed-off floor plan or a warmer thermostat all burn more. The methodology lists every source and formula.