Board Foot Calculator
Enter the thickness, width and length of your lumber to get board feet for one board or a whole order, with an optional cost.
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In inches: 1 for 4/4, 2 for 8/4, 0.75 for ¾ in.
- Per board
- 8 BF
- Total board feet
- 80
- Cubic feet
- 6.667
How this was calculated
- Board feet per board = thickness × width × length (ft) ÷ 12 = 2 × 6 × 8 ÷ 12 = 8 BF
- Total = 10 boards × 8 = 80 BF
How this board foot calculator works
A board foot is a unit of lumber volume: a board that is 1 inch thick, 12 inches wide and 12 inches long, or 144 cubic inches. Hardwood and some specialty lumber are priced per board foot, so knowing the count tells you what a project will cost. This board foot calculator takes the thickness, width and length of one board, multiplies by the number of boards, and shows the total board feet, the cubic feet and an optional price.
The formula
Board feet = thickness (inches) × width (inches) × length (feet) ÷ 12. If the length is in inches, divide it by 12 first. A 2 in × 6 in × 8 ft board is 2 × 6 × 8 ÷ 12 = 8 board feet, so ten of them are 80 board feet. At $5 per board foot that is $400.
Thickness: quarters and nominal sizes
Hardwood is sold by rough thickness in quarters of an inch: 4/4 is 1 inch, 5/4 is 1.25 inches, 6/4 is 1.5 inches and 8/4 is 2 inches. Enter the decimal inch value. Softwood dimension lumber is named by nominal size, and the real board is smaller: a 2×4 is actually 1.5 in × 3.5 in. Retailers usually charge board feet from the nominal size, while the finished board you get has less wood, so use the nominal size if you want the number a lumber yard will quote and the actual size if you want the real volume. The 2×4×8 example is 5.33 board feet nominal but 3.5 board feet of real wood.
Allow for waste
Cuts, knots, checks and planing remove wood, so buy more than the exact total. Many woodworkers add 10 to 20 percent, more for figured or defective boards. Multiply the result by 1.15 for a 15 percent allowance.
Related calculations
Board feet are a volume, 1 BF = 1/12 cubic foot, so the cubic feet line in the results lets you compare with other materials. For a rectangular box or room use the cubic feet calculator, and for soil, mulch or concrete the cubic yard calculator.
Frequently asked questions
What is a board foot?
A board foot is a volume of lumber equal to a board 1 inch thick, 12 inches wide and 12 inches long, which is 144 cubic inches or 1/12 of a cubic foot.
How do you calculate board feet?
Board feet = thickness (in) × width (in) × length (ft) ÷ 12. A board 2 in × 6 in × 8 ft is 2 × 6 × 8 ÷ 12 = 8 board feet.
How do you calculate board feet when the length is in inches?
Divide the length in inches by 12 to get feet, then use the usual formula. A 1 in × 6 in × 96 in board is 1 × 6 × 8 ÷ 12 = 4 board feet.
What does 4/4 or 8/4 lumber mean?
Hardwood thickness is quoted in quarters of an inch: 4/4 is 1 inch, 5/4 is 1.25 inches, 6/4 is 1.5 inches and 8/4 is 2 inches. Enter the decimal inch value as the thickness.
How many board feet are in a 2x4x8?
Using the nominal size, a 2×4×8 ft board is 2 × 4 × 8 ÷ 12 = 5.33 board feet. The real 1.5 in × 3.5 in board contains 3.5 board feet of wood.