About the board foot calculator
A board foot is a volume of wood equal to a board 1 in thick, 12 in wide and 1 ft long (144 in³). Hardwood dealers in the US and Canada price rough lumber per board foot, so knowing how to calculate it lets you compare quotes and plan purchases.
Elsewhere, timber is usually sold by length or by cubic metre; this calculator shows both so you can compare.
How to use it
- Enter the thickness and width. For rough hardwood use the nominal thickness (4/4 = 1 in, 8/4 = 2 in).
- Enter the length and number of boards.
- Add a waste allowance for defects and offcuts when buying rough stock.
- Enter a price per board foot (or per m³ in metric) to estimate cost.
Formula
Board feet (one board)
BF = thickness (in) × width (in) × length (ft) ÷ 12Total
BF_total = BF × quantity × (1 + waste %)Cubic metres
m³ = BF × 0.00235974- 1 board foot = 144 in³ = 0.002359737 m³ exactly.
Worked example: Ten 1 in × 6 in boards, 8 ft long, with 15 % waste
- Each board = 1 × 6 × 8 ÷ 12 = 4 BF
- 10 boards = 40 BF
- +15 % = 46 BF
Result: Buy about 46 board feet.
Assumptions and limitations
- Dealers may measure board feet on rough (nominal) dimensions and apply their own rounding rules — check how your supplier measures.
- Dimensional softwood (2×4s, etc.) is normally sold per piece or per linear foot rather than by board foot.
Frequently asked questions
How many board feet is a 2×4×8?
Using nominal dimensions, 2 × 4 × 8 ÷ 12 = 5.33 board feet. Using the actual 1.5 × 3.5 in size, it is 3.5 board feet.
What does 4/4 mean?
Quarter-inch notation for rough hardwood thickness: 4/4 is 1 in, 5/4 is 1¼ in and 8/4 is 2 in.
How do I convert board feet to cubic metres?
Multiply by 0.00235974. 1 m³ is about 424 board feet.
Sources and further reading
- National Hardwood Lumber Association (grading & board-foot measure)
- USDA Forest Products Laboratory — Wood Handbook (FPL-GTR-282)
- NIST — Unit conversion (SI and US customary units)
Results are estimates for planning purposes. See our disclaimer for details.