Board Feet Calculator
Board feet is the volume unit hardwood lumber is priced and sold by, with one board foot equal to 144 cubic inches. This calculator takes the thickness and width in inches and the length in inches, multiplies them, and divides by 144 to give board feet per board, then multiplies by the quantity for your total. Use the rough thickness your supplier charges by so the figure matches your bill.
Board feet formula
Board feet per board = thickness (in) * width (in) * length (in) / 144
Total board feet = board feet per board * number of boards
One board foot is 144 cubic inches, so dividing the volume in cubic inches by 144 converts to board feet. Multiplying by the quantity gives the total for identical boards.
Worked example
A board 1 inch thick, 6 inches wide, and 96 inches long: 1 * 6 * 96 / 144 = 4.00 board feet. For 5 identical boards, total = 4 * 5 = 20.00 board feet. At a price per board foot you can multiply for total lumber cost.
Board feet: frequently asked questions
What is a board foot?
A board foot is the standard unit for measuring hardwood lumber volume. One board foot equals 144 cubic inches: a piece 1 inch thick, 12 inches wide, and 12 inches long. It is volume, not area, so a board twice as thick at the same face dimensions is twice as many board feet.
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in inches, then divide by 144. If you measure length in feet instead, multiply thickness in inches by width in inches by length in feet and divide by 12. Multiply by the number of identical boards for the total.
Do I use rough or finished thickness?
Lumber is usually sold by its rough or nominal thickness before surfacing, expressed in quarters: 4/4 is one inch rough, 8/4 is two inches. Use the thickness the seller charges by, which is normally the rough thickness, to match the price you will pay.
Does board feet apply to plywood or sheet goods?
No. Plywood and sheet goods are sold by the sheet or by square foot, not board feet. Board feet is the unit for solid dimensional lumber and rough hardwood. For sheets, calculate area instead of volume.
Official sources
- USDA Forest Service Forest Products Laboratory: Wood and lumber measurement research. The board foot is defined as 144 cubic inches.
- USDA Forest Service: Forest products and timber measurement.
Reviewed by the CalculatorHub team, edited by James Graham, 19 June 2026. See our methodology.