A cord is always 128 cubic feet, but a cord of one species can hold nearly twice the usable heat of a cord of another. This firewood BTU chart shows how many BTUs are in a cord of firewood for 11 common species, and how to turn that into a fair cost-per-million-BTU comparison between two sellers.
A full, seasoned cord of firewood holds roughly 13 to 27 million BTU (MMBtu), depending entirely on species — the 128 cubic feet stays fixed, but denser wood packs more fuel into that same volume. One BTU (British Thermal Unit) is a small, fixed amount of heat; MMBtu is shorthand for a million of them, the standard unit for comparing firewood, heating oil, and natural gas on equal footing.
Figures are MMBtu per full, seasoned cord (128 ft³ at roughly 20 percent moisture). The "vs. red oak" column benchmarks against the most common US firewood species, so you can see at a glance how much more or less heat a cord of any given species delivers.
| Species | Weight class | MMBtu per cord | Vs. red oak |
|---|---|---|---|
| Black locust | Heavy hardwood | 26.8 | +26% |
| Hickory | Heavy hardwood | 25.4 | +19% |
| White oak | Heavy hardwood | 24.0 | +13% |
| Sugar maple | Medium hardwood | 21.3 | Baseline |
| Red oak | Medium hardwood | 21.3 | Baseline |
| Yellow birch | Medium hardwood | 20.3 | -5% |
| Green ash | Light hardwood | 19.9 | -7% |
| Cherry | Light hardwood | 18.4 | -14% |
| Tamarack | Softwood | 17.1 | -20% |
| White birch | Light hardwood | 16.5 | -23% |
| White pine | Softwood | 13.3 | -38% |
Seasoned to roughly 20 percent moisture, per full cord. Figures follow US Forest Service and state extension tables and are approximate — see all data sources.
Price per cord alone is misleading, because a cord is a fixed volume, not a fixed amount of heat. The number that actually matters is cost per million BTU: take a seller's price per cord, divide by that species' MMBtu per cord from the chart above, and you get the dollars you are really paying for heat.
Seller A quotes $180 per rick (42.7 ft³, or 0.333 cords) of red oak. Scaled to a full cord, that is $540 — and red oak carries 21.3 MMBtu per cord, so the cost per million BTU is about $25.35. Seller B quotes $500 per cord of white pine at 13.3 MMBtu — a lower cord price, but a cost per million BTU of about $37.59. Despite the higher sticker price, the red oak is the cheaper heat.
Run your own two quotes — any species, any unit — through the signature price-per-MMBtu comparator on the homepage, or read why a cord of pine costs less and heats less for more on why the cheaper cord is not always the cheaper heat.
It depends entirely on species: a full cord of seasoned firewood holds roughly 13 to 27 million BTU (MMBtu). Dense hardwoods like black locust and hickory sit near the top of that range; softwoods like white pine sit near the bottom. See the full firewood BTU chart above for all 11 species.
Black locust, at roughly 26.8 MMBtu per seasoned cord — nearly double the heat of white pine from the exact same size stack of wood.
It is the price you actually pay for heat, not for volume: take the price per cord, divide by that species’ MMBtu per cord, and you get dollars per MMBtu. A cheaper cord of a light species can cost more per MMBtu than a pricier cord of a dense one, since it delivers less heat for the same stacked volume.
The figures on this chart assume wood seasoned to about 20 percent moisture. Green, unseasoned wood of the same species holds the same wood fiber but delivers meaningfully less usable heat, because part of every BTU goes into boiling off trapped water instead of warming the room. See <a href="/guides/wet-wood-wastes-heat">why wet wood wastes half its own heat</a>.
They follow published US Forest Service and state extension-service heat-content tables for wood seasoned to roughly 20 percent moisture. Figures are averages for comparing species against each other, not lab-precise values for any single log — always confirm locally before relying on them for a dispute.
Enter two sellers' prices, units and species — the comparator normalises everything to dollars per million BTU.