How to use this calculator
- Thickness. Nominal thickness in inches (a "2-inch" 2×4 is actually 1.5 — use the nominal value for board-foot calculations).
- Width. Nominal width in inches.
- Length. Length in feet.
- Quantity & price. Number of boards plus optional $/board-foot for total cost.
Formula
Board Feet = (Thickness(in) × Width(in) × Length(ft) × Quantity) ÷ 12
Worked example
Ten 2×8 × 12 ft boards = (2 × 8 × 12 × 10) / 12 = 160 board feet. At $4.50/bd-ft, total cost is $720.
Tips for accurate results
- Hardwood is sold by the board foot (true thickness × actual width × length).
- Softwood (framing lumber) is usually sold by the linear foot or piece, not board feet.
- Always order 10–15% extra for cutting waste, defects, and miscalculation.
- Rough-sawn lumber yields about 70–80% finished after milling — factor that into hardwood orders.