Every fuel reduced to dollars per million BTU delivered — with the double-counted-efficiency trap and the face-cord trap both handled.
What does a million BTU cost you?
Wood heat content: Utah State Forestry Extension (heat per cord of dry wood — appliance efficiency applied once, here). Energy constants: EIA — propane 91,452 Btu/gal; 100,000 Btu/therm; 3,412 Btu/kWh; fuel oil ≈137,400 Btu/gal. Furnace efficiencies applied: propane/gas 95%, oil 85%. Reviewed July 2026
Cord checker — is that "cord" a cord?
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 traps in wood-heat math. First, double-counted efficiency: some published tables list "available heat" with a stove efficiency already baked in — multiply those by your stove's efficiency and wood looks 25–50% better than it is. Our species numbers are heat content of dry wood (Utah State's table), with efficiency applied exactly once, visibly. Second, moisture: green wood spends its first hours boiling off water — season it or lose a chunk of every number above.
Face cords and ricks: a full cord is a stacked 4×4×8 ft = 128 cu ft. A "face cord" or "rick" is one row — 8 ft × 4 ft × piece length — so at 16" pieces it's a third of a cord, but at 24" it's half. That's why the checker above asks for the actual dimensions instead of trusting the name. $100 for a 16" face cord = $300/cord.
Planning quantity rather than price? The firewood calculator estimates cords per winter for your house and climate.