Board Foot Calculator
Converts lumber into board feet from the nominal size, length and count. This is how hardwood and rough-sawn timber are priced.
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The formula
board feet = thickness (in) × width (in) × length (ft) ÷ 12
A board foot is a volume: one square foot of board an inch thick, 144 cubic inches. Dividing by 12 converts the inch-inch-foot product into that unit. Nominal dimensions are used by convention, which overstates the real wood by about a third for dressed lumber.
What to watch out for
Two things to know before comparing prices:
- Nominal, not actual. A 2 × 4 is counted as 8 square inches of end grain, though it measures 1½ × 3½ — about 5¼. Everyone prices the same way, so it cancels out when comparing quotes, but not when working out what you can cut from a board.
- Hardwood is sold in quarters. 4/4 is one inch nominal, 8/4 is two. The same formula applies with the quarter figure as the thickness.
Frequently Asked Questions
How do I calculate board feet?
Multiply nominal thickness by nominal width in inches, then by length in feet, and divide by 12. An 8 ft 2 × 4 is 2 × 4 × 8 ÷ 12 = 5.33 board feet.
How many board feet in a 2 × 4 × 8?
5.33. Ten of them is 53.3 board feet. A 2 × 6 × 8 is 8 board feet, and a 2 × 12 × 12 is 24.
Is a board foot the same as a linear foot?
No. A linear foot is just length. A board foot is a volume — one foot of a 1 × 12 is one board foot, but one foot of a 2 × 12 is two.