What is a board foot?
A board foot is a volume of wood 1 inch thick, 12 inches wide and 12 inches long (144 cubic inches). Hardwood is priced per board foot using its rough thickness in quarters: 4/4 is 1 inch, 8/4 is 2 inches.
Board feet = Thickness (in) × Width (in) × Length (ft) ÷ 12
Example
Ten 1 × 6 boards, 8 ft long: 1 × 6 × 8 ÷ 12 = 4 BF each, 40 BF total.
Quarter sizes
| Quarter | Rough thickness | Typical surfaced |
|---|---|---|
| 4/4 | 1 in | 13/16 in |
| 5/4 | 1-1/4 in | 1-1/16 in |
| 6/4 | 1-1/2 in | 1-5/16 in |
| 8/4 | 2 in | 1-3/4 in |
Frequently asked questions
How many board feet in a 2x4x8?
5.33 BF using nominal size (2 × 4 × 8 ÷ 12). Construction lumber is usually sold per piece, not per BF.
Do I use actual or nominal size?
Hardwood is measured by rough (nominal) thickness and actual width. Follow your lumberyard's convention.
How much extra lumber should I buy?
Add 15–30% for defects and cutting waste in furniture projects.