The comparison most sellers hope you won't run
Every heat source reduces to the same unit: dollars per million BTU of heat into the room. Wood at $250/cord of red oak through a modern stove is 250 ÷ (24.6 × 0.75) ≈ $13.55/MBtu. Propane at $2.80 through a 95% furnace is 2.80 ÷ 0.0869 ≈ $32.23. Resistance electric at 14¢ is $41.03 — but the same electricity through a heat pump at COP 3 is $13.68, which is why the modern rival to your woodpile isn't the propane truck, it's the heat pump.
Two things distort that comparison badly enough to reverse it, and both are specific to wood: tables that have already applied a stove efficiency, and wood that has not finished drying. Both are worked through below, under the two traps in wood-heat math.
Putting every fuel in the same unit
Fuels are sold in units chosen for the convenience of the seller, not for comparison. Wood comes by the cord, propane by the gallon, natural gas by the therm or the hundred cubic feet, heating oil by the gallon, pellets by the ton, electricity by the kilowatt-hour. None of those units tells you anything about heat until you convert.
The conversion is straightforward and uses published constants. Taking all four from the same place — the Energy Information Administration's Btu conversion factors — a gallon of propane contains 91,452 Btu, a therm of natural gas is 100,000 Btu by definition, a kilowatt-hour is 3,412 Btu, which is a physical constant rather than an estimate, and a gallon of heating oil is 138,500 Btu. Using one publisher's whole set matters more than it sounds: mixing a heat content from one table with an efficiency assumption from another is how comparisons quietly drift. A cord of firewood is the one input that cannot come from that list, because it depends entirely on species, which is the subject of the next section.
Divide the price by the heat content and you get dollars per Btu; multiply by a million and you have dollars per million Btu, which is the number that lets a cord and a kilowatt-hour argue with each other on equal terms. Then divide by the efficiency of the appliance that will burn it, because the fuel's energy and the heat that reaches your living room are not the same quantity.
Species is most of the value in a cord
A cord is a volume — 128 cubic feet of stacked wood — so buying a cord tells you nothing about how much heat you bought. Dense hardwoods carry far more energy in the same stack than light softwoods, and the spread is close to a factor of two.
Using Utah State University Forestry Extension's figures for dry wood, white oak runs about 29.1 million Btu per cord, sugar or hard maple about 25.5, red oak about 24.6, American elm about 20.0, quaking aspen about 18.2, ponderosa pine about 16.2, and cottonwood about 15.8. So a cord of white oak and a cord of cottonwood are the same purchase by volume and nearly a two-to-one difference in heat. If cottonwood is being offered at ten percent less than oak, it is not a deal.
This is also why "mixed hardwood" as a description is worth discounting. It can mean oak and hickory, or it can mean elm, box elder and whatever came down in the last storm. If you cannot identify what is on the truck, assume the middle of the range and pay accordingly.
The two traps in wood-heat math
The first is double-counted efficiency. Some widely circulated heat-value tables publish "available" Btu per cord with a stove efficiency already applied — often 50 or 60 percent. If you take one of those figures and multiply it by your stove's efficiency, you have applied the discount twice — and because the second multiplication can only shrink the delivered heat, the error runs in the direction people least expect: wood comes out looking more expensive than it is, not cheaper. Work it on this page's own anchor. A $250 cord of red oak at 75 percent is $13.55 per million Btu. Take a table that has already baked in 60 percent, multiply by your stove's 75 percent again, and the same cord reads $22.58 — two-thirds dearer. Start from a table baked at 50 percent and it reads $27.10, exactly twice the true figure. The species figures on this page are the heat content of the dry wood itself, with no appliance efficiency baked in, and the efficiency you enter is applied exactly once, visibly. If you are comparing against a number you found elsewhere and wood looks roughly twice as costly here as there, this is almost always why.
The second is moisture. Green firewood can be half water by weight, and every pound of that water has to be boiled off inside your stove before the wood burns properly. That energy comes out of the fuel and goes up the chimney as steam, and it drops the flue temperature enough to promote creosote as well. The published heat values assume dry wood — roughly 20 percent moisture, which for most species means split and stacked under cover for a full season, and longer for oak. Burning green wood does not just cost you efficiency; it costs you the chimney.
Appliance efficiency, honestly
Efficiency is where a lot of comparisons go soft, so use realistic numbers rather than nameplate ones. An old, uncertified airtight stove is often in the 50 to 60 percent range in real use. A modern EPA-certified stove is typically 70 to 80. An open masonry fireplace can be close to zero net, and in a drafty house it can be negative — it pulls more heated household air up the chimney than the fire delivers to the room.
On the fossil side, a modern condensing gas furnace is 90 to 97 percent, an older atmospheric one 78 to 82. Electric resistance heat, whether baseboard or a furnace element, is essentially 100 percent at the point of use. A heat pump is the exception to the whole framework, because it moves heat rather than making it: at a coefficient of performance of 3 it delivers three units of heat per unit of electricity, which is 300 percent by this accounting. COP falls as it gets colder outside, so a heat pump that runs at 3.5 in November may be at 2 in a cold snap, and cold-climate comparisons should use the lower figure.
The practical upshot in the numbers above is worth stating plainly: the modern competitor to a woodpile is not the propane truck, it is the heat pump. Wood still wins on cost when you cut your own, and it wins outright when the power is out — but a comparison that only looks at wood versus propane is fighting the last decade's fight.
The break-even prices, worked out
The calculator answers "what does each fuel cost me today." The more useful question when you are deciding whether to keep burning wood is the inverse: how far would the other fuel have to fall, or how far could a cord rise, before the answer flips. That is one division away from the same formula, and the numbers are more decisive than most people expect.
Anchor on a cord of red oak — 24.6 million Btu — at $250, burned in a modern EPA stove at 75 percent. That is 18.45 million Btu of delivered heat per cord and $13.55 per million Btu. Now run each rival backwards to the price at which it ties:
- Propane would have to fall to about $1.18 a gallon through a 95 percent furnace. At a more typical $2.80 it is not close — propane is nearly two and a half times the cost of that cord.
- Heating oil would have to fall to about $1.60 a gallon through an 85 percent furnace.
- Natural gas ties at about $1.29 a therm, which is close to what a lot of people already pay — piped gas is the one fossil fuel that genuinely competes with a cord of wood. It is also the one most readers of this page cannot get, which is exactly why propane is on the list.
- Electric resistance would have to fall to about 4.6 cents a kilowatt-hour — a third of the 14¢ this page uses as its default. Resistance heat is the one option on this list that never gets close.
- A heat pump at COP 3 ties at about 13.9 cents a kilowatt-hour — and that is the whole story of this page. Fourteen-cent electricity through a heat pump is a dead heat with $250 red oak. Not close, not a rout: a tie.
Run it the other direction and the same tie appears from the other side. Holding the rivals at the defaults above, a cord of red oak matches a COP-3 heat pump at 14¢ electricity at about $252 a cord; it matches $3.60 heating oil at about $564; it matches $2.80 propane at about $595; and it matches 14¢ electric resistance at about $757. So if firewood in your area runs $200 to $250 delivered, you are beating propane and oil by a wide margin and roughly tying a heat pump. If it runs $400 — $21.68 per million Btu — you are still beating propane and oil comfortably, and now paying about sixty percent more than the heat pump.
Two adjustments matter more than any of the above. Cutting your own collapses the cord price toward the cost of a permit, a tank of gas and a chain — call it $75 a cord in consumables, which is $4.07 per million Btu, and nothing else on the list comes within a factor of three of it. And the stove matters as much as the wood: the same $250 cord through an open fireplace at 15 percent is $67.75 per million Btu, worse than every fuel on this page including electric resistance. A fireplace is not a cheap way to heat. It is the most expensive one here.
What the dollar figure leaves out
Cost per million Btu is the right first comparison, and it is not the whole decision. Wood carries labor that the other fuels do not — cutting, splitting, stacking, hauling in, ash out — and if you cut your own, the fuel is nearly free but the hours are not. It carries risk, both from the saw and from the chimney, and an annual sweep is a real recurring cost. It requires storage space and a season of lead time, since wood you buy in October to burn in November is the wrong wood.
Against that, wood heats when the grid is down, the price does not spike with a cold snap, and on a woodlot you are already managing it is a byproduct of work you would do anyway. Those are legitimate reasons to burn wood at a cost per Btu that loses on the spreadsheet. What the spreadsheet is for is knowing by how much, so the choice is made with the number in hand rather than around it.
Planning quantity rather than price? The firewood calculator estimates cords per winter for your house and climate.