Woodworking calculator
Board Foot Calculator
A board foot is the unit hardwood lumber is sold in: one board foot is 144 cubic inches, the volume of a piece 1 inch thick, 12 inches wide, and 12 inches long. Enter your board dimensions below to get exact board feet, add a price per board foot to see the cost, and stack up several boards for a full project total.
How it works
Board feet measure the volume of rough lumber, not its surface area or its running length. The standard shop formula multiplies the three dimensions and divides by 144, the number of cubic inches in one board foot. When the length is given in feet instead of inches, the same identity simplifies to thickness times width times length-in-feet, divided by 12.
This calculator normalizes every length to inches internally, so both forms of the formula give exactly the same answer, then multiplies by the quantity of identical boards. Add separate rows for boards of different sizes and it sums the board feet, and the cost, across the whole list.
Use the nominal rough thickness for hardwood sold in quarter units: 4/4 is 1 inch, 5/4 is 1.25 inches, 8/4 is 2 inches. Lumberyards bill board feet on the rough size before surfacing, so a planed 0.75 inch board is still sold as 4/4, or one full inch, of thickness.
Worked example
Three boards of 4/4 stock (1 in thick), 6 in wide and 8 ft long: (1 × 6 × 96) / 144 = 4 board feet each, so three boards = 12 board feet.
Frequently asked questions
What is a board foot?
A board foot is a volume of lumber equal to 144 cubic inches, the same as a piece 1 inch thick by 12 inches wide by 12 inches long. Most hardwood is priced and sold per board foot.
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in inches and divide by 144. If the length is in feet, multiply thickness by width by length-in-feet and divide by 12 instead.
Do I use the rough or the finished thickness?
Use the nominal rough thickness the yard bills by. A surfaced 0.75 inch board is still sold as 4/4 (one inch) because board feet are figured on the rough size before the board is planed.
Is a board foot the same as a linear foot?
No. A linear foot measures length only, while a board foot measures volume. A long narrow board and a short wide board can share the same board feet but have very different linear feet.
How do I price a whole project at once?
Add each board as its own row with its dimensions and quantity, enter the price per board foot, and the calculator sums the board feet and the cost across every row to give a project total.
Related calculators
Sources
These calculators are for planning and estimation. Engineering results (shelf sag, wood movement) use published average material properties; real boards vary by grade, grain, moisture and defects. Verify load-bearing designs with a professional.