Board Feet Calculator
Rough lumber, timbers, and hardwood are sold by the board foot, not the linear foot. Pick the nominal size, enter length and quantity, and get the FBM total and cost — computed from nominal dimensions, the way the lumberyard counts it.
Planning tool — results are estimates for quoting and ordering, not engineering or building-code advice.
Common questions
How do you calculate board feet?
Nominal thickness (in) × nominal width (in) × length (ft) ÷ 12. An 8-foot 2×6 is 2 × 6 × 8 ÷ 12 = 8 board feet.
Why nominal and not actual size?
Board feet is defined on nominal dimensions — a 2×4 counts as 2" × 4" even though it dresses to 1-1/2" × 3-1/2". Using actual sizes under-counts by roughly 30%, which is the classic FBM mistake.
What is 5/4 lumber?
"Five-quarter" — nominal 1-1/4" thickness, common for decking boards and stair treads. It counts as 1.25" in the board-foot math, and it's one of the presets here.
Related: Spacing calculator · Free estimate template
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