How Many BTU Are in a Cord of Wood?
The EIA uses about 20 million BTU per cord as an average. Seasoned dense hardwoods run roughly 24–29 million and softwoods about 16–17 million. What reaches your room is lower: a 70%-efficient stove turns a 20 million BTU cord into about 14 million useful BTU.
Gross versus useful heat
| Wood | Gross million BTU | Useful at 70% |
|---|---|---|
| Average (EIA) | 20 | 14.0 |
| Sugar maple or red oak | 25.9 | 18.1 |
| Pine | 17.1 | 12.0 |
Species values are from forestry charts that differ by a million BTU or two (best firewood by BTU). They assume wood at about 20% moisture; wet wood wastes energy boiling off water (seasoning).
What a cord replaces
Using the 20 million BTU average and ignoring appliance efficiency, one cord equals about 219 gallons of propane, 144 gallons of heating oil or 1.2 tons of pellets. After typical efficiencies, a cord is closer to 180 gallons of propane (is firewood cheaper than propane?). Compare prices with the fuel cost calculator.
FAQ
How many BTU are in a face cord?
About a third of a cord with 16-inch logs, roughly 6.7 million BTU at the 20 million average.
Does a bigger stove give more BTU per cord?
No. The cord holds a fixed amount of energy; the stove determines how much becomes useful heat.
Is a million BTU the same as an MMBtu?
Yes. MMBtu means one million BTU.