What Is a Board Foot?
A board foot (BF, FBM, or BDFT) is a unit of volume: a piece of wood measuring 12 in × 12 in × 1 in (144 cubic inches or one-twelfth of a cubic foot). North American lumberyards use this unit to price rough-sawn hardwood and softwood.
How Is It Calculated?
Formula
Board Feet = Thickness (in) × Width (in) × Length (ft) ÷ 12
Multiply the result by the number of pieces to get the project total.
A Worked Example
You have four boards measuring 2 in × 10 in × 8 ft. The calculation is done with these two steps :
- Per board:
2 × 10 × 8 ÷ 12 = 13.33 BF - Project total:
13.33 BF × 4 = 53.33 BF
How Do You Calculate Board Feet in a Log?
This quick reference table shows board-foot yields for standard 1.5 × 3.5 in (2×4) lumber at common lengths. Simply find your board length in feet and read off the corresponding board-feet value to speed up your material take-off and minimize waste. Sawmills estimate yield with log-scaling rules:
| Length (ft) | Board feet | Length (ft) | Board feet |
|---|---|---|---|
| 6 | 4 | 16 | 10 ⅔ |
| 8 | 5 ⅓ | 18 | 12 |
| 10 | 6 ⅔ | 20 | 13 ⅓ |
| 12 | 8 | 22 | 14 ⅔ |
| 14 | 9 ⅓ | 24 | 16 |
(Calculation: 1.5 × 3.5 × length ÷ 12.)
How Do You Measure a Board Foot?
- Measure thickness and width in inches at the narrowest point of the board.
- Measure the actual length in feet (ignore the nominal length printed on the tag).
- Apply the board-foot formula—or simply use the calculator above.
How Many Board Feet Are in a 2 × 4?
A modern “2 × 4” actually measures 1 ½ in × 3 ½ in. Use the table below for quick reference:
| Length (ft) | Board feet | Length (ft) | Board feet |
|---|---|---|---|
| 6 | 4 | 16 | 10 ⅔ |
| 8 | 5 ⅓ | 18 | 12 |
| 10 | 6 ⅔ | 20 | 13 ⅓ |
| 12 | 8 | 22 | 14 ⅔ |
| 14 | 9 ⅓ | 24 | 16 |
(Calculation: 1.5 × 3.5 × length ÷ 12.)
Board Foot vs. Linear Foot
- Board foot measures volume—thickness, width, and length.
- Linear foot measures length only, regardless of thickness or width.
Because a board foot reflects total volume, it captures waste in thicker or wider stock. Linear-foot pricing is more common for surfaced lumber with uniform cross-sections.
Final Tip
Use this calculator to compare quotes, forecast material costs, and optimize lumber purchases—and keep these formulas handy so you can verify your numbers right on the jobsite.
