Board Foot Calculator
Calculate nominal lumber board feet per piece and for a bundle. Use nominal thickness, width, length, and a count of matching boards.
How the result changes
Only board length changes; all other inputs stay at your current values. The line illustrates the formula across the shown range. This is not a forecast of real-world outcomes.
About this calculation
A board foot is a volume unit used in lumber pricing, equivalent to a one-foot-long board one foot wide and one inch thick. This tool converts familiar nominal board dimensions and a piece count into that pricing quantity. Calculate board foot for construction problems.
Formula
board feet = length in feet × width in inches × thickness in inches ÷ 12
Worked example
With Board length: 8 ft, Nominal width: 6 in, Nominal thickness: 1 in, Boards: 10, board feet per piece is 4 board ft.
Inputs and units
Enter length in feet and width and thickness in inches. Many retail boards are sold under nominal sizes that differ from dressed dimensions, so match the dimension convention used on the actual supplier quote.
- Board length (ft): Measure the lumber length in feet.
- Nominal width (in): Use the nominal inch width when the seller prices nominal board feet.
- Nominal thickness (in): Use the nominal inch thickness that matches the lumber quote.
- Boards: Enter the number of equal-size pieces.
Calculation and worked example
Multiplying foot length by inch width and inch thickness gives an intermediate foot-inch-squared quantity. Dividing by 12 converts width to feet and yields board feet; multiply that per-piece amount by the board count In compact notation, board feet = length in feet × width in inches × thickness in inches ÷ 12.
An 8 ft board nominally 6 in wide and 1 in thick contains 8 × 6 × 1 ÷ 12 = 4 board feet. Ten boards of those dimensions represent 40 board feet before any cut waste.
How to use the answer
This is a measure of lumber volume, not exposed surface area or linear feet. Ten boards with the same board-foot total can have very different lengths or thicknesses, which matters when planning actual cuts.
Multiply total board feet by a quoted price per board foot to estimate raw lumber cost. Calculate different board sizes separately and add their totals; using one average size can obscure a mix of thick and thin stock.
Assumptions and checks
Every counted board has identical nominal dimensions and is a rectangular solid. The estimate excludes knots, saw kerf, planing loss, offcuts, and any supplier-specific board-measure rounding rules.
The divisor is 12 when length is already in feet. If all three dimensions are measured in inches, the divisor would be 144; mixing those two conventions makes a twelvefold error.
A 12 in wide, 1 in thick, 1 ft long board equals exactly one board foot. Use that reference piece to check the scale of your entered board dimensions.
Common questions
What does the board feet per piece result represent?
It is nominal cubic lumber volume expressed as board feet for one piece, with a second result for all identical pieces.
What should I check before relying on this result?
Confirm whether the seller uses nominal or actual dressed dimensions, and account for cutting losses separately from purchased board feet.
Inputs
- Board length (ft)
- Nominal width (in)
- Nominal thickness (in)
- Boards