Lumber Calculator
Enter the number of pieces, nominal size (2×4, 2×6, etc.), and length to calculate total board feet and your project cost.
1. Number of pieces
2. Nominal size
Actual size for 2×4: 1.5" × 3.5"
3. Length per piece
4. Waste & price (optional)
Your Lumber Estimate
Board feet (with 10% waste)
38.5 bf
Pieces needed
10
Board feet (no waste)
35.0 bf
Nominal size
2×4 × 8 ft
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How board feet are calculated
Board feet = (Thickness × Width × Length) ÷ 12
All dimensions in inches × inches × feet.
| Size | bf per 8-ft piece | bf per 12-ft piece |
|---|---|---|
| 2×4 | 5.3 | 8.0 |
| 2×6 | 8.0 | 12.0 |
| 2×8 | 10.7 | 16.0 |
| 2×10 | 13.3 | 20.0 |
| 1×6 | 4.0 | 6.0 |
Frequently Asked Questions
How do I calculate board feet of lumber?
Board feet = (Thickness in inches × Width in inches × Length in feet) ÷ 12. For example, a 2×6 that is 8 feet long = (2 × 6 × 8) ÷ 12 = 8 board feet.
How much lumber do I need to frame a wall?
For a 10 ft wall at 16-inch stud spacing: about 8 studs + 30 linear feet of plate lumber (2 bottom plates + 1 top plate). Add 10–15% waste for corners and openings.
What is the actual size of a 2×4?
A nominal 2×4 is actually 1.5 inches × 3.5 inches. The nominal size is the rough-cut size; the actual size is smaller after drying and planing. Always use actual dimensions for coverage calculations.
How many board feet do I need for a deck?
For a 12×16 ft deck (192 sq ft), plan for 400–600 board feet of decking boards plus framing lumber. Add 10–15% for waste and spacing gaps between boards.
Formula: Board feet = (Thickness" × Width" × Length ft) ÷ 12. Waste applied to total board feet. See our methodology page for all constants.