Board foot calculator
Add up the board feet in a stack of lumber, with the cost and an overage if you want them. Enter each size once with how many boards of it you have. Count the exact volume, or the way a hardwood lumberyard tallies it.
Overage is your own allowance for defects, offcuts and mistakes. We don’t suggest a figure: we haven’t found three sources that agree on one.
Board feet
46.67 bd ft
- Volume
- 3.889 ft³
- Linear length
- 40 ft
From the standard, NHLA Rules (2019)
Why: A board foot is 144 cubic inches, so each board is thickness × width × length ÷ 12; these come to 46.67 bd ft.
Why these numbers?
The situation
5 boards, 40 linear ft in all, counted at the sizes you entered.
From your input: the boards and how to count them
What that means
A board foot is the wood in a board 1 in thick, 12 in wide and 12 in long: 144 cubic inches.
One source: National Hardwood Lumber Association, the grading body that defines the unit , sources [1]
The number
Thickness (in) × width (in) × length (ft) ÷ 12 for each board, added up: 46.67 bd ft.
Arithmetic: exact by definition
Sources
How board feet work
A board foot is the wood in a piece 1 inch thick, 12 inches wide and 12 inches long: 144 cubic inches. A board holds its thickness in inches times its width in inches times its length in feet, divided by 12. A 1 × 6 that is 8 feet long is 1 × 6 × 8 ÷ 12 = 4 board feet.
Hardwood is sold by the board foot at its rough thickness, written in quarters of an inch: 4/4 is 1 inch, 8/4 is 2 inches. Type quarters straight into the thickness field. A board that was surfaced to 13/16 inch is still billed as 4/4; tick “surfaced” and the calculator counts it at the rough size it was planed from.
Exact volume or lumberyard tally?
Exact volume multiplies the sizes you enter, nothing rounded. Use it for a cut list or a project estimate. Lumberyard tally follows the hardwood grading rules: each board’s surface area is rounded to a whole square foot before it is multiplied by the thickness, and anything thinner than 1 inch is counted as 1 inch. Use it to check a bill from a hardwood dealer. The two can differ by a board foot or two on a pile of random-width boards.
Softwood framing lumber (2x4s and the like) is also named by a nominal size, bigger than the board itself. Its real dimensions are on the lumber sizes chart. Hardwood thicknesses before and after surfacing are on the hardwood thickness chart. For standing timber or logs, use the log board feet calculator.
We give no lumber prices: no source publishes them in a form we could cite and keep current. Enter your yard’s price per board foot to see the cost.