What one board foot is
A board foot (BF) is a lumber volume unit used across North American hardwood trade. By definition it equals a piece 1 inch thick, 12 inches wide, and 1 foot long — 144 cubic inches of wood. Yards price many hardwoods and specialty stocks by the board foot rather than by the piece.
The formula
Board feet for one board = (thickness in inches × width in inches × length in feet) ÷ 12. Multiply by the number of identical boards for a total. The American Hardwood Export Council publishes the same W × L × D ÷ 12 relationship for determining board feet. This site’s calculator uses that contract and also reports cubic feet as board feet ÷ 12.
Thickness in quarters
Rough hardwood is often sold in quarter-inch thickness names: 4/4 is 1 inch, 5/4 is 1.25 inches, 6/4 is 1.5 inches, 8/4 is 2 inches. Enter the thickness that matches how the board is billed. If the invoice says 8/4, use 2 in the thickness field unless your seller states otherwise.
Surface measure vs board feet
In NHLA hardwood grading practice, surface measure (SM) comes first: width in inches × length in feet ÷ 12, typically rounded to the nearest whole foot. For 4/4 stock, SM and board feet align; thicker stock multiplies SM by the thickness factor. Home workshop estimates usually skip SM rounding and use the continuous formula — fine for shopping lists, not a substitute for a graded mill tally.
Checks before you order
Ask whether the quote uses nominal labels or measured faces, whether waste for defects is included, and whether length is random or fixed. Keep a short note of the dimensions you entered so the delivery ticket can be compared to your estimate.
Sources
Primary definition and measurement wording: American Hardwood Export Council, “Grading sawn lumber — Measurement” (americanhardwood.org). Trade discussion of NHLA surface-measure rounding appears in industry knowledge bases such as WoodWeb. Local yard rules still control the final invoice.