What Is a Board Foot?
By Nick · Updated
A board foot is a piece of wood 12 inches wide, 12 inches long and 1 inch thick: 144 cubic inches. To count board feet, multiply thickness × width in inches by length in feet and divide by 12. An 8-foot 2 × 4 is 5.33 board feet.
Count board feet for your listKey figures
- 1 board foot = 12 in. × 12 in. × 1 in. = 144 cubic inches.
Source: NHLA Rules for the Measurement and Inspection of Hardwood (2023)
- Softwood uses the nominal (name) size, like 2 × 4.
Source: American Softwood Lumber Standard, PS 20-20 (NIST)
- Hardwood uses rough thickness in quarters: 4/4 is 1 inch, 8/4 is 2.
Source: NHLA Rules for the Measurement and Inspection of Hardwood (2023)
- Boards thinner than 1 inch count as 1 inch.
Source: NHLA Rules for the Measurement and Inspection of Hardwood (2023); 7 CFR §1217.4 (softwood lumber board foot)
How do you calculate board feet?
Thickness (in) × width (in) × length (ft) ÷ 12. If the length is in inches, divide by 144 instead.
For a 2 × 6 that is 12 feet long:
- 2 × 6 = 12
- 12 × 12 ft = 144
- 144 ÷ 12 = 12 board feet
Multiply by how many boards you have, then add up each size on your list.
Source: NHLA Rules for the Measurement and Inspection of Hardwood (2023)
Do you use the actual or the nominal size?
For softwood, the nominal size. A 2 × 4 counts as 2 by 4 inches even though it is planed smaller.
That rule comes from the American Softwood Lumber Standard, which sets how construction lumber is tallied.
Source: American Softwood Lumber Standard, PS 20-20 (NIST)
How is hardwood measured?
In quarters of an inch of rough thickness: 4/4 is 1 inch, 5/4 is 1¼, 6/4 is 1½ and 8/4 is 2.
Board feet are counted before planing. A 4/4 board surfaced to 13/16 inch still counts as 1 inch thick.
Source: NHLA Rules for the Measurement and Inspection of Hardwood (2023)
How do you count boards thinner than 1 inch?
As 1 inch thick. A ¾-inch board is tallied the same as a 1-inch board.
So an 8-foot board ¾ inch thick and 6 inches wide is 4 board feet, not 3.
Source: NHLA Rules for the Measurement and Inspection of Hardwood (2023); 7 CFR §1217.4 (softwood lumber board foot)
How many board feet are in common boards?
Board feet for each nominal size and length:
| Board | 8 ft | 10 ft | 12 ft |
|---|---|---|---|
| 1 × 6 | 4 | 5 | 6 |
| 1 × 12 | 8 | 10 | 12 |
| 2 × 4 | 5.33 | 6.67 | 8 |
| 2 × 6 | 8 | 10 | 12 |
| 2 × 8 | 10.67 | 13.33 | 16 |
| 4 × 4 | 10.67 | 13.33 | 16 |
Source: American Softwood Lumber Standard, PS 20-20 (NIST)
Other questions
How many board feet are in a 2 × 4 × 8?
5.33 board feet.
Source: American Softwood Lumber Standard, PS 20-20 (NIST)
What is the difference between a board foot and a lineal foot?
A lineal foot is just length. A board foot is volume, so it depends on thickness and width too.
How we worked this out
Board feet follow the published lumber rules: the NHLA hardwood rules, the American Softwood Lumber Standard (PS 20) and 7 CFR §1217.4. Every figure is calculated by the same code as the board foot calculator.
Sources
- NHLA Rules for the Measurement and Inspection of Hardwood (2023)
- American Softwood Lumber Standard, PS 20-20 (NIST)
- 7 CFR §1217.4 (softwood lumber board foot)