Board foot calculator
A board foot is 1 inch thick, 12 inches wide and 12 inches long: 144 cubic inches of lumber. Enter the thickness, width, length and quantity for each size to get board feet, and a price per board foot to get the cost.
Thickness and width are in inches and length is in feet. Marks work too: 1 1/2", 8' 6", 2.4 m. The starting row is ten 2x4 boards, 8 feet long.
The board foot formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12, times the number of pieces.
Ten 2x4x8' boards: 2 × 4 × 8 ÷ 12 = 5 1/3 board feet each, and 5 1/3 × 10 = 53 1/3 board feet.
The same boards in cubic feet: 53 1/3 ÷ 12 = 4.44 cu ft.
Use the nominal size, so a 2x4 counts as 2 by 4. Hardwood is quoted by thickness in quarters (4/4 is 1 inch, 8/4 is 2 inches), and it is usually sold by the board foot. Framing lumber is usually sold by the piece, and mills often price it per thousand board feet (MBF).
| Nominal size | 8 ft | 10 ft | 12 ft | 16 ft |
|---|---|---|---|---|
| 1x4 | 2 2/3 | 3 1/3 | 4 | 5 1/3 |
| 1x6 | 4 | 5 | 6 | 8 |
| 1x8 | 5 1/3 | 6 2/3 | 8 | 10 2/3 |
| 1x10 | 6 2/3 | 8 1/3 | 10 | 13 1/3 |
| 1x12 | 8 | 10 | 12 | 16 |
| 2x4 | 5 1/3 | 6 2/3 | 8 | 10 2/3 |
| 2x6 | 8 | 10 | 12 | 16 |
| 2x8 | 10 2/3 | 13 1/3 | 16 | 21 1/3 |
| 2x10 | 13 1/3 | 16 2/3 | 20 | 26 2/3 |
| 2x12 | 16 | 20 | 24 | 32 |
| 4x4 | 10 2/3 | 13 1/3 | 16 | 21 1/3 |
| 4x6 | 16 | 20 | 24 | 32 |
| 6x6 | 24 | 30 | 36 | 48 |
Questions
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. Multiply by the number of pieces. A 2x4 that is 8 feet long is 2 × 4 × 8 / 12 = 5 1/3 board feet.
How many board feet are in a 2x4x8?
5 1/3 board feet, or 5.33. Ten of them are 53 1/3 board feet.
How many board feet are in a 2x4x12?
8 board feet: 2 × 4 × 12 / 12 = 8.
Do board feet use the nominal size or the actual size?
The nominal size. A 2x4 is counted as 2 inches by 4 inches even though a dry piece measures about 1 1/2 by 3 1/2 inches. Enter the nominal size.
How do I figure board feet for hardwood sold in quarters?
Hardwood thickness is quoted in quarters of an inch: 4/4 is 1 inch, 5/4 is 1 1/4 inches, 8/4 is 2 inches. Enter the thickness in inches, for example 1 or 1 1/4.
How do I get the cost from board feet?
Multiply the board feet by the price per board foot. 53 1/3 board feet at $3.50 per board foot is $186.67.
How do I convert board feet to cubic feet?
Divide by 12. One board foot is 144 cubic inches, which is 1/12 of a cubic foot. 53 1/3 board feet is 4.44 cubic feet.