Calculate board feet from thickness, width, length, and board count. Includes waste allowance and cost estimate at your price per board foot.
Added Jun 16, 2026
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Enter a value for thickness to see your result.
Calculates lumber volume in board feet from thickness, width, length, and board count. Optionally includes a waste allowance and total cost at your price-per-board-foot. One board foot equals 144 cubic inches of wood.
Board Feet = (Thickness × Width × Length in feet) ÷ 12
A 1×6×8 board contains 4 board feet (1 × 6 × 8 ÷ 12). Ten boards = 40 BF. With 15% waste = 46 BF. At $4.50/BF the base cost is $180, with waste $207.
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A board foot (BF) is a unit of lumber volume equal to 144 cubic inches — the volume of a board 1 inch thick, 12 inches wide, and 12 inches long (1" × 12" × 12" = 144 in³). It is the standard unit for pricing hardwood lumber. Softwood dimensional lumber (2×4s, 2×6s) is often sold by the linear foot instead.
Board feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12. Example: a 1" × 6" × 8ft board = (1 × 6 × 8) ÷ 12 = 4 board feet. For multiple boards, multiply by the board count.
Use nominal dimensions for board foot calculations when buying from a lumber yard — that's how they price it. A nominal 1×6 is actually 0.75" × 5.5", but lumber yards charge by the nominal 1×6 board foot measurement. Use actual dimensions only when calculating material needed for a project (cutting lists).
Add 10–15% for clean, clear dimensional lumber with minimal knots. Add 15–20% for knotty or lower-grade lumber. Add 20–25% for reclaimed, rough-sawn, or character-grade hardwoods with more defects. The waste allowance covers end splits, knots in critical positions, and cutting errors.