Lumber Calculator
Calculate board feet and lumber quantities for any project.
| Nominal | Actual (inches) | Board Feet / Linear Foot |
|---|---|---|
| 1×4 | 0.75" × 3.5" | 0.0182 BF/lf |
| 1×6 | 0.75" × 5.5" | 0.0286 BF/lf |
| 2×4 | 1.5" × 3.5" | 0.0365 BF/lf |
| 2×6 | 1.5" × 5.5" | 0.0573 BF/lf |
| 2×8 | 1.5" × 7.25" | 0.0755 BF/lf |
| 2×10 | 1.5" × 9.25" | 0.0964 BF/lf |
| 2×12 | 1.5" × 11.25" | 0.1172 BF/lf |
| 4×4 | 3.5" × 3.5" | 0.0851 BF/lf |
A "2×4" nominally is 2" × 4" but the actual dimension after drying and planing is 1.5" × 3.5".
Frequently Asked Questions
What is a board foot and how do I calculate it?
A board foot is a unit of lumber volume = 1 inch thick × 12 inches wide × 12 inches long (144 cubic inches). Formula: Board feet = (thickness in inches × width in inches × length in feet) ÷ 12. For a 2×6 board, 8 feet long: (2 × 6 × 8) ÷ 12 = 8 board feet.
Why is a "2×4" not actually 2 inches by 4 inches?
Nominal dimensions (2×4, 2×6, 4×4) refer to the rough-sawn size before kiln drying and planing. Actual dimensions are smaller: a 2×4 measures 1.5" × 3.5", a 2×6 is 1.5" × 5.5", and a 4×4 is 3.5" × 3.5". This calculator uses actual dimensions for coverage calculations like deck board spacing.
How many deck boards do I need?
Calculate deck area, then account for board width (actual), spacing between boards (typically 1/8" or 3mm), and waste (10–15% for angled cuts or patterns). For a 12ft × 16ft deck (192 sq ft) using 5/4×6 decking (actual 5.5" wide) with 1/8" gaps: approximately 155 linear feet / board length per row × rows = total boards.