Lumber Calculator
Enter your board dimensions and quantity to calculate total board feet - the standard unit lumber is priced and sold by.
Last updated: September 5, 2026
Frequently asked questions
How do I calculate board feet?
Multiply thickness in inches × width in inches × length in feet, then divide by 12. A 1.5×5.5×8 ft board (actual dimensions of a nominal 2×6×8) works out to 5.5 board feet.
Why use actual dimensions instead of nominal?
A nominal 2×6 actually measures about 1.5×5.5 inches after milling and drying - using nominal dimensions overstates board feet and your order.
Why is lumber priced and measured in board feet?
A board foot is a volume measurement (12 in × 12 in × 1 in), which lets lumber of different lengths, widths, and thicknesses be compared and priced on a consistent basis - it's more useful than linear feet once boards vary in width or thickness.
Why is a 2x4 not actually 2 inches by 4 inches?
Lumber is named by its nominal (pre-milling) size, but planing and drying reduce the actual finished dimensions - a nominal 2x4 measures about 1.5 by 3.5 inches actual. This calculator uses actual dimensions for board-foot calculations, since that's the real material you're buying.
How many board feet for 15 boards of nominal 2×4×10 ft lumber?
Using actual dimensions of 1.5×3.5 inches: 1.5 × 3.5 × 10 ÷ 12 = 4.375 board feet per board. For 15 boards that's about 65.6 total board feet.
Does board length affect board feet the same way width and thickness do?
Yes, all three dimensions contribute proportionally - board feet is thickness × width × length ÷ 12, so doubling any one of the three (with the others held constant) doubles the board feet, whether that's a longer board, a wider board, or a thicker one.
How is a board foot different from a linear foot of lumber?
A linear foot only measures length, ignoring width and thickness, so it can't compare boards of different sizes fairly. A board foot is a volume measurement (12×12×1 inch), which is why lumber of varying widths and thicknesses is priced by board feet rather than by linear foot.