Board foot calculator, with price and metric sizes
Board feet from thickness, width and length, in inches or millimeters, plus the cost if you know the price per board foot. The formula is on the page so you can check it.
I made this because every lumber list I read is priced per board foot and I kept doing the math on a napkin. Type the sizes of one board and how many you need. It works in inches or millimeters.
Everything is calculated in your browser. Nothing is saved or sent.
How it works
A board foot is a volume: 1 inch thick, 12 inches wide and 12 inches long, which is 144 cubic inches.1 So board feet = thickness (in) × width (in) × length (in) ÷ 144. With the length in feet, divide by 12 instead.
Millimeters are converted with 1 inch = 25.4 mm exactly.2 Cubic meters come from the same definition: one board foot is 144 × 0.0254³ m³, about 0.00236 m³.
Use the thickness the yard charges for. Wikipedia notes that rough lumber is usually measured on its sawn size and planed softwood on nominal sizes, so a “2×4” is not 2 by 4 inches in your hand.1 If you are unsure, ask the yard which size they bill.
Common questions
How many board feet is a 1×6 that is 8 feet long?
On nominal sizes, 1 × 6 × 8 ÷ 12 = 4 board feet. On the actual planed size the volume is smaller. Which one you pay for depends on the yard.
Is a board foot the same as a square foot?
Only for a board 1 inch thick. A board foot is a volume, so a 2-inch board covering one square foot is 2 board feet.