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Board Foot Calculator
Thickness × width × length ÷ 12, times the piece count, gives the board feet for a lumber order. Add a price per board foot to get the material cost. Also searched as the board feet calculator or lumber board foot calculator.
Formula
How the Math Works
Board feet = thickness in × width in × length ft ÷ 12 × quantity
Worked example: twelve 2×6s, 10 ft long, at $1.25 per board foot.
- 2 in × 6 in × 10 ft = 120, and 120 ÷ 12 = 10 bd ft per piece
- 10 × 12 pieces = 120 bd ft
- At $1.25 per board foot: 120 × 1.25 = $150.00
Units & assumptions
Thickness and width are in inches, and length is in feet. One board foot is 144 in³ (1 in × 12 in × 12 in). Lumber yards normally figure board feet on nominal sizes (a 2×6 counts as 2 in × 6 in even though it measures 1.5 in × 5.5 in). Hardwood is sold on rough thickness in quarters (4/4 = 1 in, 8/4 = 2 in). If quantity is left blank, it counts as 1.
Planning tool, not a PE stamp. Your spec, drawings, and supplier still win.
Field Questions
What is a board foot?
A board foot is a volume of wood equal to 144 cubic inches, which is a piece 1 in thick, 12 in wide, and 12 in long.
How many board feet are in a 2×4×8?
2 × 4 × 8 ÷ 12 = 5.33 board feet, using nominal dimensions.
Do I use nominal or actual lumber sizes?
Most yards price board feet on nominal dimensions (2×6, 4/4). Use actual measurements only if your supplier sells on actual or surfaced sizes.
How do I figure lumber cost by the board foot?
Multiply the total board feet by the price per board foot. For example, 120 bd ft × $1.25 = $150.00.