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Board Foot Calculator

Carpentry, Calculators Published 10/18/2007 by Ben Erickson

While lumber is commonly sold by the piece in building supply stores, wholesalers and hardwood dealers usually price their stock by the board foot. Ask for a dozen two by fours eight feet long at your local sawmill, and you’ll be told that what you really want is 64 board feet of lumber.

It’s not as confusing as it sounds as long as you remember that a board foot is a measure of volume equal to a square foot one inch thick. So a 1” by 12” a foot long and a 2” by 6” of the same length both equal one board foot. Rough lumber measurements in width and thickness are used when calculating board feet even if the lumber has been planed down.

To calculate the number of board feet, use the following formula:

thickness (inches) x width (inches) x length (feet) ÷ 12 = board feet

Below are some common widths and their equivalent in board feet per foot of length:

• 1” x 4” x 1’ = 0.33 bd. ft.
• 1” x 6” x 1’ = 0.50 bd. ft.
• 1” x 8” x 1’ = 0.67 bd. ft.
• 1” x 10” x 1’ = 0.83 bd. ft.
• 1” x 12” x 1’ = 1.0 bd. ft.
• 2” x 4” x 1’ = 0.67 bd. ft.
• 2” x 6” x 1’ = 1.0 bd. ft.
• 2” x 8” x 1’ = 1.33 bd. ft.
• 2” x 10” x 1’ = 1.67 bd. ft.
• 2” x 12” x 1’ = 2.0 bd. ft.

To find the number of board feet, multiply the number above by the length of the board, then multiply the total by the number of boards needed.

While you can do the math with a pencil and paper, it’s a lot easier to use our online board foot calculator: