Board Foot Calculator
Add up the board feet in a lumber order, several pieces at once with 4/4, 5/4, 6/4 and 8/4 hardwood thickness presets, then add a waste factor and see the cost at a price per board foot or per thousand board feet (MBF).
Board foot calculator
| Pieces | Thickness | Width (in) | Length (ft) | Board feet |
|---|---|---|---|---|
Board foot formula
A board foot is 144 cubic inches: a board 1 inch thick, 12 inches wide and 1 foot long. Board feet = thickness (in) × width (in) × length (ft) ÷ 12, or thickness × width × length (all in inches) ÷ 144.
Examples: a 1 × 6 × 8 ft board: 1 × 6 × 8 ÷ 12 = 4 BF. An 8/4 board 10 inches wide and 12 feet long: 2 × 10 × 12 ÷ 12 = 20 BF. A 5/4 × 8 in × 10 ft board: 1.25 × 8 × 10 ÷ 12 = 8.33 BF.
Quarter thickness and nominal sizes
Hardwood is sold rough by the quarter inch: 4/4 is 1 inch, 5/4 is 1¼, 8/4 is 2. Board feet are figured on the rough (nominal) thickness, so a 4/4 board planed to ¾ inch is still priced as 1 inch thick. Softwood dimensional lumber (2×4, 2×6) is usually sold by the piece or linear foot, but board feet use the nominal size too: a 2×4 × 8 ft is 5.33 BF.
Waste factor and price
Add 15% to 20% for knots, checks, defects and offcuts on rough hardwood (more for figured wood or many short parts; less for clear S4S stock). Lumberyards quote hardwood per board foot, and sawmills and wholesale often per MBF, a thousand board feet: $950 per MBF is $0.95 per BF.
Common questions
How do I calculate board feet?
Thickness (in) × width (in) × length (ft) ÷ 12. A 1×6 that's 8 ft long is 4 board feet.
How many board feet are in a 2x4x8?
5.33 BF using nominal size (2 × 4 × 8 ÷ 12).
What does 4/4 lumber mean?
Four quarters of an inch, or 1 inch rough thickness. 8/4 is 2 inches.
Do you use actual or nominal thickness for board feet?
Nominal (rough) thickness: a 4/4 board surfaced to ¾ inch is still figured at 1 inch.
What is MBF?
1,000 board feet, the unit sawmills and wholesalers use to price lumber.
Sources
- USDA Forest Service, Forest Products Laboratory: Wood Handbook
- NHLA: Rules for the measurement and inspection of hardwood lumber
Related
General information, not financial, tax or legal advice. Check important numbers with the official source before acting on them.