Firewood BTU Chart

Firewood BTU chart by species

Each row is the heat in one full cord of seasoned wood, 128 cubic feet stacked, in millions of BTU. These are gross figures: all the heat in the wood, before any goes up the chimney. Where the extension tables disagree, the chart shows the range, and the calculator above uses the median. The second column is the seasoned weight of the same cord, because weight explains most of the first column.

Ranges span the extension sources. Heat is gross heat in air-dried wood, before stove losses. A dash means no sourced figure.

The heat figures come from extension tables published by the University of Nebraska, the University of Minnesota, Penn State, Virginia Tech, Utah State and South Dakota State. Most species have three or more of them behind the range. Black locust, yellow birch, ponderosa pine and osage orange have two, and Douglas-fir rests on a single table.

Why denser wood gives more heat per cord

Pound for pound, seasoned wood holds about the same heat whatever the species. In the University of Minnesota’s table, dividing any row’s heat by its weight gives about 6,400 BTU per pound at 20% moisture, whether the row is hickory or white pine. The University of Arkansas uses one figure, 6,604 BTU per pound of wood, for every species in its table.

So the heat in a cord depends on how many pounds of wood it holds, which comes down to density. The USDA Forest Service’s Wood Handbook lists specific gravity, a measure of density, for each species, and a few of them set beside the chart fall in the same order:

That is why lodgepole pine isn’t in the chart. The one table we found for it, from Utah State, gives 21.1 million BTU for a 2,610 lb cord. That works out to about 8,100 BTU per pound, far above the 6,400 the other tables imply, and no second source settles it. Lodgepole’s specific gravity is 0.41 in the Wood Handbook, next to ponderosa pine’s 0.40, so expect a cord to give heat closer to ponderosa pine than to Douglas-fir.

Why BTU charts disagree

If you’ve seen red oak listed at about 12 million BTU per cord somewhere else, you were probably reading delivered heat. The Minnesota bulletin gives a second column at 50% heating efficiency, which is half the gross figure: 12.0 million BTU for red oak. The University of Arkansas table lists red oak at about 12.2 million and states a 50% burning efficiency. How much of the gross heat reaches your room depends on the stove or fireplace, so this chart gives the fuel side only.

The other differences come from what each table assumes is in a cord. A cord is 128 cubic feet of stacked space, but the solid wood in it ranges from 50–100 cubic feet depending on the size of the pieces. Minnesota’s table assumes 85 cubic feet at 20% moisture. Nebraska’s table labels its column “dry” without giving a moisture figure. Those assumptions are one reason white oak spans 25.7–29.1 million BTU across sources while hickory stays within 27.5–28.

Best firewood to burn

On heat per cord, four dense hardwoods lead: osage orange at 30.7–32.9 million BTU, black locust at 27.9–29.3, hickory at 27.5–28 and white oak at 25.7–29.1. Sugar maple, red oak, American beech, yellow birch and white ash form the next group at 23.6–27.5. Black walnut, paper birch, black cherry, elm and red maple give 18.7–22.2, along with Douglas-fir. Ponderosa pine, aspen, eastern white pine and cottonwood sit at the bottom, at 13.5–18.2 between them.

These tables measure heat per cord and don’t rate smoke, sparks or how easily a species splits. For most buyers the best firewood is the densest wood they can get properly seasoned at a fair price per million BTU, which the next three sections cover.

Seasoned firewood: what moisture does to heat

Seasoned firewood has dried in the air after being cut and split, and every number in the chart assumes it. Minnesota’s table is calculated at 20% moisture, Penn State assumes 20% for an air-dried cord, and Virginia Tech’s figures are also at 20%.

EPA says wood burns best at a moisture content below 20%. University of Maryland Extension says freshly cut wood has to dry below that point to burn efficiently, and Nebraska’s NebGuide calls for six to 12 months of air drying for freshly cut trees. None of these sources puts a number on the heat lost when wood is burned green, so the chart and the calculator give heat for seasoned wood only. Burn wood before it dries and you can expect less heat than the chart shows.

“Seasoned” on a sales listing doesn’t mean one fixed standard. South Dakota State’s extension service calls wood seasoned below 28% moisture, a looser line than EPA’s 20%. Ask how the seller defines it, or check with a moisture meter. Weight is a rougher check: a green cord of red oak weighs 4,888 lb against 3,528–3,757 lb seasoned, and the cord weight guide has the gap for each species.

How long to season firewood

EPA’s advice is to split, stack, cover and store firewood for at least six months if it’s a softwood and at least a year if it’s a hardwood. Extension services fall in the same 6–12 months window. Penn State gives 6 to 12 months to reach about 20% moisture and notes that some species may need more than six. Virginia Tech puts it at 9 to 12 months for most locations. South Dakota State asks for at least nine months split, off the ground and under cover.

EPA and South Dakota State both count the time from splitting. If you buy seasoned wood, ask when it was split and how it has been stored since. If you cut your own, Nebraska’s rule of thumb is to cut a year ahead of when you’ll burn it.

Heat per dollar: compare species and prices

Two cords at the same price can hold very different amounts of heat: by the typical figures, a cord of red oak has about two-thirds more than a cord of eastern white pine (24 against 14.3 million BTU). To compare species, divide each price per full cord by that wood’s million BTU per cord from the chart. That gives dollars per million BTU, and the lower number is the better buy. If a seller quotes a face cord, convert it first: a face cord of 16-inch wood is a third of a full cord. The firewood calculator does that conversion for any unit, and the cord of wood price guide covers what sellers charge.

Worked example: hickory or red oak?

The calculator’s typical figures are 27.7 million BTU per cord for hickory and 24 for red oak. Hickory gives more heat per dollar as long as its price per cord is less than 27.7 ÷ 24 = 1.15 times the red oak price, so it can cost up to about 15% more and still win. Run the same test on eastern white pine at 14.3 million BTU: 14.3 ÷ 24 = 0.60, so a cord of white pine has to cost less than 60% of the red oak price to give more heat per dollar.

The Heat tab above does the multiplication for any amount. Enter 2 cords of red oak and it shows 48 million BTU, with 48–49.2 million across sources.

Hardwood vs softwood firewood

The chart has three softwoods (Douglas-fir, ponderosa pine and eastern white pine), with 14.3–20.7 million BTU per cord between them. Its 16 hardwoods run from 13.5 to 32.9 million. Most of them give 18.7 million or more, but the two lightest, aspen at 14–18.2 and cottonwood at 13.5–15.8, sit at the bottom with eastern white pine (14.3–15.6) and ponderosa pine (15–16.2). Douglas-fir, at 20.7 from its one source, lands among paper birch (20.3–20.8) and black cherry (19.9–20.4).

Density explains the overlap. In the Wood Handbook, aspen’s specific gravity is 0.38 and cottonwood’s 0.40, the same range as ponderosa pine at 0.40 and eastern white pine at 0.35, so a hardwood can be as light as a pine. EPA does treat the two groups differently for seasoning, giving softwoods six months and hardwoods at least a year.