Firewood Heating Cost Calculator
Estimate how many cords of firewood a heating season needs and what it costs, by wood species, stove efficiency and your seasonal heat demand.
How it works
Usable heat/cord = species BTU × efficiency · Cords = season demand ÷ usable heat per cord · Cost = cords × price · $/MMBTU = price ÷ (usable heat in MMBTU)
Firewood value comes from the heat a cord actually delivers into the room, not its purchase price alone. Dense hardwoods like oak pack roughly 24 million BTU per cord versus about 15 million for softwoods, and only the fraction your stove’s efficiency captures becomes useful heat — an open fireplace wastes most of it up the chimney. Dividing seasonal demand by the usable heat per cord gives the cords to buy, and pricing per million usable BTU lets you compare wood against gas or electric heat fairly.
Worked example
A 60-million-BTU season on oak (24 M BTU/cord) through a 70% stove yields 24 × 0.70 = 16.8 M usable BTU per cord, so 60 ÷ 16.8 ≈ 3.6 cords. At $250 a cord that is about $893, or roughly $14.88 per usable million BTU.
Frequently asked questions
What exactly is a cord?
A full cord is a stacked pile measuring 4 ft × 4 ft × 8 ft, or 128 cubic feet of wood and air. Beware "face cords" or "ricks," which are only one row deep — typically about a third of a full cord — and should cost proportionally less.
Why does wood species matter so much?
Denser hardwoods contain more wood mass per cord, so oak and hickory release far more heat than the same volume of pine. Softwoods light easily and are fine for shoulder-season fires, but you burn through more cords for the same warmth.
Does moisture content change this?
Yes. Green, unseasoned wood spends much of its energy boiling off water and delivers far less usable heat. Season firewood to under about 20% moisture for a year before burning to get close to these figures.
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This calculator is for educational purposes. Double-check important results before acting on them.