Board Foot Calculator
Built by Johnny Alto · free, no sign-up · updated July 26, 2026
Enter your board's thickness, width, and length to get the board feet, the unit hardwood is priced and sold by. Add a quantity and a price per board foot and it also totals your cost, so you can compare boards and budget a project before you get to the lumberyard.
Total0board feet
Each board0board feet
Estimated cost$0at your price
One board foot is 144 cubic inches, a piece 1 inch thick by 12 inches wide by 1 foot long. Nominal thickness is figured on rough size, so a board sold as 4/4 (1 inch) counts as 1 inch even after planing. Charge quarter thicknesses as their nominal value (5/4 = 1.25).
How to calculate board feet
A board foot is a measure of volume, not length: it is 144 cubic inches of wood, the amount in a piece one inch thick, twelve inches wide, and one foot long. To find the board feet in any board, multiply thickness in inches by width in inches by length in feet, then divide by twelve. If your length is in inches instead, divide by 144.
Hardwood is sold this way because boards come in random widths and lengths, so pricing by the board foot is fair regardless of shape. A wide, thick, long board simply contains more board feet than a thin, narrow, short one.
Watch the thickness convention
Rough lumber is measured by its nominal, pre-surfaced thickness written in quarters: 4/4 is one inch, 5/4 is an inch and a quarter, 8/4 is two inches. You are charged on that nominal thickness even after the board is planed thinner, so enter the quarter value, not the finished thickness. Always buy 15 to 20 percent extra to cover defects, snipe, and cutting waste.
Recommended gear
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Frequently asked questions
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 1 by 6 inch board that is 8 feet long is 4 board feet.
What is a board foot?
A unit of volume equal to 144 cubic inches, the wood in a piece 1 inch thick, 12 inches wide, and 1 foot long. Hardwood is priced by the board foot.
Does board foot use nominal or actual thickness?
Nominal, the rough pre-surfaced thickness in quarters. A 4/4 board counts as 1 inch and 8/4 as 2 inches even after planing, so use the quarter value.
How much extra lumber should I buy?
Add 15 to 20 percent to your calculated board feet to cover knots, cracks, snipe, and cutting waste.
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This calculator gives estimates for planning only; always confirm against your own measurements and species research. Some links are to our buying guides, which contain affiliate links. As an Amazon Associate I earn from qualifying purchases.
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