What is a board foot?
A board foot is a volume of wood: 144 cubic inches, the same as a board 1" thick, 12" wide and 12" long. Hardwood dealers and many lumberyards price by the board foot so boards of different sizes can be compared.
Board foot formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12
Or with every dimension in inches, divide by 144. Some examples:
- 2×4×8: 2 × 4 × 8 ÷ 12 = 5.33 bd ft
- 2×8×16: 2 × 8 × 16 ÷ 12 = 21.33 bd ft
- 1×12×12: 1 × 12 × 12 ÷ 12 = 12 bd ft
- 4×4×10: 4 × 4 × 10 ÷ 12 = 13.33 bd ft
Nominal vs. actual size
A "2×8" actually measures about 1½" × 7¼" after drying and planing. Board feet are normally figured on the nominal size (2 × 8), and that's how lumberyards bill. If you're buying rough-sawn hardwood, measure actual thickness in quarters (4/4 = 1", 8/4 = 2") and use that.
Estimating cost
If your yard quotes per board foot, enter that price. If it quotes per piece or per linear foot, divide to get a per-board-foot price so you can compare suppliers: price per bd ft = price per piece ÷ bd ft per piece. A $14.50 2×8×16 is 14.50 ÷ 21.33 = $0.68 per board foot.
FAQ
How do you calculate board feet?
Multiply thickness in inches by width in inches by length in feet, then divide by 12. A 2×6 that is 10 feet long is 2 × 6 × 10 ÷ 12 = 10 board feet.
Do you use nominal or actual dimensions for board feet?
Lumberyards use nominal dimensions for softwood framing lumber (a 2×4 is figured as 2" × 4"). For rough hardwood, use the actual rough thickness in quarters, like 4/4 or 8/4.
How many board feet are in a 2×4×8?
A 2×4×8 is 5⅓ board feet (2 × 4 × 8 ÷ 12 = 5.33).
What is the difference between a board foot and a linear foot?
A linear foot is just length, one foot of a board of any size. A board foot is volume, 144 cubic inches. A 2×12 has 2 board feet in every linear foot. A 1×6 has half a board foot per linear foot.