Use this free board foot calculator to find the board feet in a single board or a whole lumber order, add waste, and estimate the cost at your yard’s price per board foot.
How to calculate board feet
A board foot is a volume of wood equal to a board 1 inch thick, 12 inches wide and 12 inches long (144 cubic inches). The formula is:
Board feet = Thickness (in) × Width (in) × Length (ft) ÷ 12
If you measure length in inches, divide by 144 instead of 12.
Example
You need ten 8/4 walnut boards, each 6 inches wide and 8 feet long. 8/4 means 2 inches thick, so one board is 2 × 6 × 8 ÷ 12 = 8 board feet. Ten boards = 80 board feet. At $14 per board foot, the order costs about $1,120 before waste.
How much is a board foot?
Price depends on species, grade and region. Hardwoods such as walnut, cherry and white oak are usually sold by the board foot, while construction softwood (2×4s, 2×6s) is usually sold by the piece or linear foot. Enter your supplier’s price above to get a total.
Board foot chart for common lumber sizes (8 ft long)
| Nominal size | Board feet per 8 ft board |
|---|---|
| 1 × 4 | 2.67 |
| 1 × 6 | 4.00 |
| 1 × 8 | 5.33 |
| 1 × 12 | 8.00 |
| 2 × 4 | 5.33 |
| 2 × 6 | 8.00 |
| 2 × 8 | 10.67 |
| 2 × 10 | 13.33 |
| 2 × 12 | 16.00 |
Nominal vs. actual size
A “2×4” actually measures about 1.5 × 3.5 inches after drying and planing. Lumber yards normally calculate board feet on the nominal size, so use nominal numbers when you check a quote. For rough-sawn hardwood, thickness is given in quarters: 4/4 = 1 inch, 5/4 = 1.25 inches, 8/4 = 2 inches.
Board feet vs. square feet vs. linear feet
- Board feet measure volume (thickness × width × length).
- Square feet measure surface area only (width × length).
- Linear feet measure length only, regardless of width or thickness.
Frequently asked questions
How many board feet are in a 2×4×8?
2 × 4 × 8 ÷ 12 = 5.33 board feet (using nominal size).
How much waste should I add?
Woodworkers often add 15–30% for defects, knots and offcuts when buying rough hardwood. For dimensional lumber, 5–10% is common.
Can I use this for logs?
No. Logs are measured with log scales (Doyle, Scribner or International 1/4″) that account for sawing loss. A dedicated log board foot calculator is coming soon.