How the board foot calculator works
A board foot is a volume of wood 12 in × 12 in × 1 in, or 144 cubic inches. With length in feet, the formula simplifies to:
Hardwood thickness is often given in quarters: 4/4 is 1 in, 5/4 is 1¼ in and 8/4 is 2 in, measured rough before planing. Board feet are calculated on these nominal dimensions. Softwood construction lumber such as 2×4s is usually sold by the piece or linear foot instead. Add 15% to 30% for defects, knots and cutting waste in furniture projects.
Worked example
Ten 8/4 boards 6 in wide and 8 ft long are 2 × 6 × 8 ÷ 12 = 8 board feet each, 80 BF in total. At $4.00 per board foot they cost $320.00. Allowing 15% waste, plan on 92 BF ($368).
Frequently asked questions
What is a board foot?
A volume of wood equal to 144 cubic inches, such as a board 1 in thick, 12 in wide and 12 in long.
How do I calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12.
What does 4/4 lumber mean?
Four quarters of an inch, or 1 in nominal thickness before surfacing.
Why is hardwood sold by the board foot?
Hardwood boards come in random widths and lengths, so volume is the fairest way to price them.
Updated October 2026. Results are estimates for education, not financial or medical advice. All math runs in your browser; nothing you type is sent anywhere.