How do you calculate board feet?
A board foot is 144 cubic inches of wood: 1 in thick, 12 in wide and 12 in long. Board feet = thickness (in) × width (in) × length (ft) ÷ 12, so a 1 × 6 in board 8 ft long is 4 board feet, and 10 of them make 40 board feet.
Worked example: ten 1 × 6 boards, 8 ft long
- Multiply thickness by width: 1 × 6 = 6.
- Multiply by length in feet: 6 × 8 = 48.
- Divide by 12: 48 ÷ 12 = 4 board feet per board.
- Multiply by the number of boards: 4 × 10 = 40 board feet.
Board feet chart for common sizes
Calculated from the nominal size in inches. Hardwood is usually sold by the rough thickness in quarters, so 4/4 lumber counts as 1 in and 8/4 as 2 in.
| Size (in) | 8 ft | 12 ft | 16 ft |
|---|---|---|---|
| 1 × 4 | 2.67 | 4.00 | 5.33 |
| 1 × 6 | 4.00 | 6.00 | 8.00 |
| 1 × 8 | 5.33 | 8.00 | 10.67 |
| 2 × 4 | 5.33 | 8.00 | 10.67 |
| 2 × 6 | 8.00 | 12.00 | 16.00 |
| 2 × 8 | 10.67 | 16.00 | 21.33 |
| 2 × 10 | 13.33 | 20.00 | 26.67 |
| 2 × 12 | 16.00 | 24.00 | 32.00 |
How the calculator works
Board feet per piece = thickness (in) × width (in) × length (ft) ÷ 12
Total board feet = board feet per piece × number of pieces
Cubic feet = board feet ÷ 12
The division by 12 comes from the definition: with length in feet, thickness × width × length gives twelfths of a board foot. If you measure length in inches, divide by 144 instead.
Frequently asked questions
What is a board foot?
A board foot is a unit of lumber volume equal to 144 cubic inches, the volume of a board 1 in thick, 12 in wide and 12 in long.
How many board feet are in a 2 × 4 × 8?
Using the nominal size, 2 × 4 × 8 ÷ 12 = 5.33 board feet.
What is the difference between board feet and linear feet?
Linear feet measure length only. Board feet measure volume, so they also account for the thickness and width of the board.
How many board feet are in a cubic foot?
Twelve. A cubic foot is 1,728 cubic inches, and 1,728 ÷ 144 = 12 board feet.