Board-foot calculator for rectangular lumber
Calculate board feet from actual thickness, width, length and quantity, with the formula and a worked example.
Applies to: DIY rectangular panel and board planning. United States English; user-entered dimensions and prices.
A board foot is a volume equal to a 12 × 12 × 1 in block. Use actual rectangular dimensions to estimate volume; confirm how your supplier measures and bills rough lumber.
Calculate board feet
1 in × 6 in × 8 ft × 1 = 4 board feet.
The formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12 × quantity.
This calculation measures rectangular volume. It does not account for taper, defects, machining loss, purchase grading or cutting yield.
Reference: Wood-Mizer: What is a Board Foot?, retrieved November 11, 2026.