Lumber Calculator
Calculate board feet for framing, decking, fencing, and woodworking projects
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Lumber List
Board feet = (T × W × L) ÷ 12
Quick fill from common size:
Enter lumber dimensions and quantities to calculate board feet
Tips & Notes
- •Nominal lumber dimensions are larger than actual: a 2×4 is actually 1.5"×3.5".
- •Board feet = (thickness × width × length) ÷ 12 — thickness and width in inches, length in feet.
- •Order 10–15% extra for framing; 15–20% for decking and flooring to account for defects and cuts.
- •Air-dry or kiln-dry lumber before using inside — green lumber will shrink and warp.
- •Pressure-treated lumber is required for all ground contact and exterior structural applications.
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Pro tips for lumber
- ›Nominal lumber dimensions are larger than actual: a 2×4 is actually 1.5"×3.5".
- ›Board feet = (thickness × width × length) ÷ 12 — thickness and width in inches, length in feet.
- ›Order 10–15% extra for framing; 15–20% for decking and flooring to account for defects and cuts.
- ›Air-dry or kiln-dry lumber before using inside — green lumber will shrink and warp.
- ›Pressure-treated lumber is required for all ground contact and exterior structural applications.
Frequently asked questions
How do I calculate board feet?▾
Board feet = (thickness in inches × width in inches × length in feet) ÷ 12. A 2×4 that's 8 feet long is (2 × 4 × 8) ÷ 12 = 5.33 board feet. The calculator above does this for any combination of board sizes.
What are actual lumber dimensions?▾
Nominal sizes are larger than actual. A 2×4 is actually 1.5" × 3.5". A 2×6 is 1.5" × 5.5". A 1×6 is 0.75" × 5.5". This is because lumber is rough-cut to the nominal size, then planed smooth.
How much lumber do I need to frame a 10×12 wall?▾
A 10' wall at 16" stud spacing uses 9 studs, plus top and bottom plates (2 × 10' = 20 linear feet). For 2×4 framing, that's about 92 board feet. Add 10–15% for waste, headers, and blocking.
How much does framing lumber cost in 2026?▾
Common 2×4×8 studs run $3–$6 each ($0.75–$1.50/board foot). Pressure-treated 2×4×8 runs $7–$11. Premium kiln-dried lumber and hardwoods are sold by the board foot at $3–$15+ depending on species.
When do I need pressure-treated lumber?▾
Use pressure-treated for any ground-contact framing, deck posts, deck joists below 6" of soil, sill plates on concrete, and outdoor structures. Indoor framing and above-ground non-contact framing can use standard SPF (spruce-pine-fir).