Calculation details
Planning estimate only. Verify dimensions, waste, coverage, product specifications, and local requirements before purchasing materials.
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What does this calculator estimate?
A board foot calculator estimates lumber volume for pricing. Enter thickness, width, length, and quantity to get board feet per piece and total.
- Board feet = T × W × L ÷ 12
- 1 bd ft = 144 in³
- The standard lumber pricing unit
Why lumber is priced in board feet
Lumber is sold by volume, not length — a 2×4×8 and a 2×6×8 contain different amounts of wood. Board feet normalize volume so mills and yards can price consistently. Rough vs finished sizes matter: a '2×4' is actually 1.5×3.5 inches.
Limitations to watch for
The formula uses nominal thickness and width for rough lumber, but surfaced (S4S) boards are smaller than nominal — use actual dimensions for accuracy. Hardwood is priced per board foot; softwood (2x lumber) is usually per linear foot.
How to use it in practice
Measure thickness and width in inches and length in feet, then multiply and divide by 12. Multiply by the price per board foot for cost. Add ~10% for waste and defects when buying.
['Enter thickness and width in inches.', 'Enter length in feet and quantity.', 'The tool computes board feet per piece and total.']
What a board foot is
A board foot is 1 inch × 12 inches × 1 foot of lumber: 144 cubic inches. A 2×6 that is 8 feet long contains 2×6×8 = 96 board-inches ÷ 12... using the formula (thickness × width × length) ÷ 12: 2 × 6 × 8 ÷ 12 = 8 board feet. The calculator converts any dimensions.
Why lumber is sold this way
Board feet standardize pricing across sizes: a 1×12 and a 2×6 of the same length can contain the same volume, so the price per board foot compares directly. The calculator makes quotes comparable.
Nominal vs. actual dimensions
Lumber is sold by nominal size — a '2×4' is actually 1.5×3.5 inches. Board-foot pricing uses nominal for softwood framing in most markets; hardwood is priced on the actual measured board foot. The calculator matches the convention you choose.
A worked example
Ten 2×6×8 boards: each is 8 board feet, total 80 board feet. At $3.50 per board foot, the material is $280. The calculator returns the total and the cost.
Waste in wood projects
Framing and furniture projects waste 10–20 percent to cutting, knots, and defects. Ordering above the calculated volume avoids mid-project trips. The calculator's waste input covers it.
How this calculator works
Formula
Board feet = thickness (in) × width (in) × length (ft) ÷ 12. One board foot = 1 inch × 1 foot × 1 foot (144 in³).
Worked example
A 1″ × 6″ × 8′ board: 1 × 6 × 8 ÷ 12 = 4 board feet.
Assumptions to verify
- Nominal or actual dimensions are entered consistently.
- One board foot = 144 in³.
- Quantity multiplies the per-piece volume.
Frequently asked questions
What is a board foot?
A lumber volume unit: 1″ × 1′ × 1′, or 144 cubic inches. It's how hardwood is priced.
How do I calculate board feet?
Thickness (in) × width (in) × length (ft) ÷ 12. A 1″×6″×8′ board = 1×6×8÷12 = 4 board feet.
What's the difference between nominal and actual size?
A '2×4' is nominally 2×4 but actually 1.5×3.5 after surfacing. Use actual sizes for accurate volume.
How much lumber do I need for a project?
Calculate each piece's board feet, sum them, and add 10–15% for waste and defects.
Is softwood priced in board feet?
Usually not — 2× lumber is sold per linear foot; board feet is the standard for hardwood and rough lumber.
How do I price a board?
Multiply board feet by the price per board foot (e.g., 4 bd ft × $5 = $20).
What is the difference between board foot and square foot?
Square feet measure area (flooring); board feet measure volume (lumber). They serve different pricing purposes.
Is lumber priced by board foot?
Yes — standardizing price across sizes, especially for hardwoods and framing.
Should I add waste?
10–20% for cutting and defects, depending on the project.
Cite this tool
BoringToolsKit. “Board Foot Calculator.” boringtoolskit.com/board-foot-calculator/ (reviewed 2026-08-25). Free to reference in articles, syllabi, and answer posts with a link.
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