Board Foot Calculator
Enter a board's thickness, width, and length to get its volume in board feet — the unit sawmills and timber yards use to measure and price lumber.
One board, one number
Enter thickness and width in inches and length in feet, and the calculator returns the board-foot volume using (T × W × L) ÷ 12.
Mind the units
Thickness and width are in inches but length is in feet — keep them in those units or the board feet will be wrong.
What is a board foot?
The unit of lumber volume
This board foot calculator turns three measurements — a board's thickness, width, and length — into its volume in board feet, the standard unit used to buy, sell, and estimate hardwood and rough-sawn timber. A board foot is exactly 144 cubic inches: the amount of wood in a board 1 inch thick, 12 inches wide, and 1 foot long. Despite the name it measures volume, not length or area, which is why a thick plank holds more board feet than a thin one of the same face size. Knowing the board-foot count lets you compare prices between yards, budget a project, and order the right amount of stock in one go.
Enter the thickness and width in inches and the length in feet to get the board-foot volume instantly.
Board feet are the thickness times the width times the length, divided by 12. The division by 12 reconciles the mixed units — inches for thickness and width, feet for length — because one board foot is 144 cubic inches and a 12-inch foot converts the length.
Board feet = (T × W × L) ÷ 12Take a board that is 1 inch thick, 6 inches wide, and 8 feet long. Multiply the thickness and width to get the cross-section, 1 × 6 = 6 square inches; multiply by the 8-foot length for 6 × 8 = 48 inch-inch-feet; then divide by 12 to land on 48 ÷ 12 = 4 board feet. If you are ordering several identical boards, multiply that single-board figure by the piece count to size the whole order.
The formula is exact, but a couple of practical points decide whether your number matches the lumber yard.
Nominal vs. actual size, and consistent units
Decide whether you are using the nominal (full) size or the actual planed size before you start. Rough-sawn hardwood is usually billed at its nominal dimensions, while planed softwood is smaller than its name — a "2×4" is really about 1.5 in × 3.5 in. Keep thickness and width in inches and length in feet; if a board's length is given in inches, divide it by 12 to get feet first. This calculator measures volume only and does not add a waste allowance for cuts or defects.