Firewood calculator: how many cords is my stack?
Figures checked Nov. 10, 2026
Measure your stack's length, height and depth, and the calculator divides the volume by 128 cubic feet, the size of a cord. It rounds down, so it doesn't add wood. Further down, a second tool estimates how many cords you need for a winter, from your own figures.
Measure your stack
The sums behind this tool are tested against 2 worked examples printed in published sources, and 17 checks in all, including the limits where it gives no number.
How to measure a firewood stack
Measure the length along the ground, the height from the ground to the top, and the depth from front to back. For a single row, the depth is the log length.
Measure stacked wood only. A legal cord is ranked and well stowed, meaning pieces in rows, touching and parallel. A loose, thrown pile holds less wood than its size suggests.
Cords for a winter
The sums behind this tool are tested against 29 checks, including the limits where it gives no number.
What the result means
The result shows cubic feet and cords, both rounded down. A full cord is 128 cubic feet, usually stacked 4 ft high x 4 ft wide x 8 ft long.
It is an estimate only. If you think a delivery is short, your state's weights and measures office can help.
How much firewood do I need for a winter?
There is no single answer: it depends on your home, your climate, your stove and your wood. We don't guess any of those. Instead, the winter tool on this page works from figures you know.
- How much you burn a week: cords a week, times the weeks of the heating season.
- The fuel you used last winter: oil, propane, gas, electricity or pellets, with your old system's efficiency.
Wood type and stove efficiency
When you start from last winter's fuel, the tool also asks which wood you'll burn and how efficient your stove is. Wood type matters: a cord of red oak holds about 24 million Btu, and a cord of eastern white pine about 14.3 million. See best firewood for every species.
If you're not sure of the wood, the tool shows a range. The high end of wood needed uses the lowest species figure we hold, and the low end uses the EIA's average cord of 20,000,000 Btu.
The Department of Energy puts new wood stoves at 65–83 percent efficient, and the tool starts at the low end. Older airtight stoves run lower, the University of Missouri Extension says, which means more wood. Open fireplaces aren't offered; the DOE says most traditional fireplaces are still energy losers.
Using last winter's fuel
Type how much oil, propane, gas, electricity or pellets you used last winter, and the efficiency from your old system's label, often shown as AFUE. The tool turns that into the heat your home used, then into cords.
It counts last winter's fuel at the top of the recorded range of heat values, so the estimate leans toward more wood, not less. A very large result gives no number; ask a qualified heating professional instead.
To weigh up the cost against your current fuel, use the fuel cost comparer. It works per million Btu, so every fuel is compared like for like.
Questions people ask
How many cords of wood do I need for winter?
It depends on your home, climate, stove and wood. Use the winter tool on this page with how much you burn a week, or the fuel you used last winter.
How do I measure a cord of wood?
Stack it tightly, then multiply length, height and depth in feet. Divide by 128 to get cords.
Does a loose pile of wood count as a cord?
Not by volume. A legal cord is ranked and well stowed, so stack the wood before you measure it.
How many cords are in a stack of firewood?
Type the stack's length, height and depth into the calculator. It gives cubic feet and cords, rounded down.
Sources for this page
5 figures and 2 wood types, each with its source
Every figure on this page, with its source. Open one to see the exact words on the source page and how it was checked.
Legal cord (volume of ranked and well-stowed wood): 128 cubic feet Official
From Connecticut Dept. of Consumer Protection: Firewood and Stove Wood Regulations (quotes NIST Handbook 130, 2016), which says: “The amount of wood that is contained in a space of 128 cubic feet when the wood is ranked and well stowed.” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026. A blind check looked it up again on Nov. 10, 2026 without seeing our figure: the two agreed.
Standard cord dimensions: 4 ft high x 4 ft wide x 8 ft long Official
From Maine Revised Statutes, Title 10, section 2302 Definitions, which says: “A standard cord is a unit of measure of wood products 4 feet wide, 4 feet high and 8 feet long, or its equivalent, containing 128 cubic feet when the wood is ranked and well stowed.” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Open fireplace efficiency: no official figure Not confirmed
From US DOE Energy Saver: Wood and Pellet Heating, which says: “most traditional fireplaces are still energy losers.” Open the source (opens in a new tab)
Checked Nov. 9, 2026.
Heat content of a cord of wood (generic, species not known): 20,000,000 Btu per cord Official
From US EIA: Units and calculators explained, British thermal units (Btu), which says: “1 cord=20,000,000 Btu” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026. A blind check looked it up again on Nov. 10, 2026 without seeing our figure: the two agreed.
Wood stoves (efficiency): 65–83% (HHV) Official
From US DOE Energy Saver: Wood and Pellet Heating, which says: “New advanced non-catalytic combustion stoves often have efficiencies of 65% to 75%, HHV.” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check re-opened the source page and matched it on Nov. 9, 2026.
Red oak: 24 million Btu per cord; 3,757 lb seasoned; 4,888 lb green Official
Heat: from Virginia Tech (Bond & Downing): Firewood, Facts, Follies and Forest Management (Woods & Wildlife 2013), which says: “Red oak | 3,757 | 24” Open the source (opens in a new tab)
Weight: from Virginia Tech (Bond & Downing): Firewood, Facts, Follies and Forest Management (Woods & Wildlife 2013), which says: “Red oak | 3,757 | 24” Open the source (opens in a new tab)
Green weight: from Utah State University Extension Forestry (Kuhns & Schmidt): Wood Heating, Table 1 Firewood Facts, which says: “Oak, Red | 4888 | 3528 | 24.6” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check matched this wood's row against the published table, cell by cell, on Nov. 9, 2026.
Eastern white pine: 14.3 million Btu per cord; 2,250 lb seasoned Official
Heat: from Virginia Tech (Bond & Downing): Firewood, Facts, Follies and Forest Management (Woods & Wildlife 2013), which says: “White pine | 2,236 | 14.3” Open the source (opens in a new tab)
Weight: from Utah State University Extension Forestry (Kuhns & Schmidt): Wood Heating, Table 1 Firewood Facts, which says: “Pine, White | (blank) | 2250 | 15.9” Open the source (opens in a new tab)
Checked Nov. 9, 2026. A second check matched this wood's row against the published table, cell by cell, on Nov. 9, 2026.