Lumber Calculator
Measurement · Updated July 2026
Enter your lumber dimensions, quantity, and price to find total board feet and estimated cost for your project.
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Results
Estimates only. Add extra for waste and confirm with your supplier.
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How do I calculate lumber board feet?
Board feet = (thickness in × width in × length ft) ÷ 12, times quantity. Multiply by price per board foot for cost.
Estimating a lumber order
List each board size and quantity, then total the board feet to compare prices and plan your haul. Add roughly 10% for cutting waste and the occasional warped or split board you'll cull at the rack.
Nominal vs. actual size
Dimensional lumber is sold by nominal size, but the finished board is smaller — a 2×4 actually measures 1.5 in × 3.5 in. Use actual dimensions for spacing and clearances, and nominal sizes when ordering.
How to use this calculator
- 1Enter thickness and width in inches.
- 2Enter length, quantity, and price.
- 3Read board feet and cost.
Frequently asked questions
What is dimensional lumber?
Lumber cut to standard sizes (like 2×4). Note nominal sizes are slightly larger than actual finished dimensions.
How much extra lumber should I buy?
Add about 10% for cutting waste, mistakes, and culling warped or damaged boards.
Why is a 2x4 not actually 2 by 4 inches?
The nominal size is the rough-cut dimension; planing and drying reduce a 2×4 to about 1.5 in × 3.5 in.
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