Board Foot Calculator
Board feet for a piece of lumber — from its nominal thickness, width, and length — times how many you need.
Your project
Material estimate only — confirm quantities against your own measurements and the product packaging before you buy. Round up and keep a little extra for cuts, waste, and mistakes.
What you need
Total
—
Total board feet
— bf
Per board
— bf
Est. cost
—
Shopping list
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How we calculate it
board feet = (thickness_in × width_in × length_ft) / 12 • total = per board × quantity
Assumptions & sources
- Uses NOMINAL dimensions by lumber-trade convention — a “2×10” is figured as 2 × 10, not its milled 1.5 × 9.25 — source: standard lumber definition
- 1 board foot = 144 cubic inches (a 1 in × 12 in × 12 in board)
- Price per board foot varies by species, grade, and region — check current local pricing
Formulas reviewed against manufacturer spec sheets and industry standards. Last verified 2026.
What is a board foot?
A board foot is a unit of lumber volume: 144 cubic inches, or a piece 1 inch thick, 12 inches wide, and 1 foot long. The formula is thickness × width (in inches) × length (in feet), divided by 12 — using the nominal size stamped on the lumber.
Tips
- Nominal, not actual: Lumber is priced by its nominal size (2×4, 2×10), even though the milled board is a bit smaller. Use the nominal numbers here.
- Multiply by quantity: Board feet are how hardwood is usually sold — total your boards to compare a project’s cost across species and suppliers.
- Watch the length units: This formula expects length in feet. If your length is in inches, divide the whole result by 12 again.
Common questions
How many board feet in a 2×10×12?
Twenty. Board feet = (2 × 10 × 12) ÷ 12 = 20 board feet, using nominal dimensions.
Are board feet based on nominal or actual size?
Nominal — the size the lumber is called (2×4, 2×10), which is how it’s priced, not the slightly smaller milled dimensions.
How is board feet different from linear feet?
Linear feet measure length only; board feet measure volume (thickness × width × length), so they account for how thick and wide the board is.