Lumber Calculator
Calculate board feet, pieces needed, and project costs instantly
Input Values
Recommended: 5-10% framing, 10-15% decking
Results
Enter values to calculate
Quick Examples
How to Use the Lumber Calculator
Our free lumber calculator helps you estimate the exact amount of lumber needed for your construction project, whether you're building a deck, installing flooring, or framing a wall. Simply enter your project dimensions and lumber specifications to get instant calculations.
The calculator provides comprehensive results including the number of boards needed, board feet, linear feet, and total cost. It also accounts for waste factors to ensure you have enough material to complete your project without multiple trips to the lumber yard.
Understanding Lumber Measurements
Board Feet
A board foot is a unit of measure for lumber volume. One board foot equals 144 cubic inches (12" × 12" × 1"). The formula is: (thickness in inches × width in inches × length in feet) ÷ 12. This is the standard unit used for pricing lumber.
Nominal vs. Actual Size
Lumber dimensions are typically listed as nominal sizes, which differ from actual dimensions. For example, a 2×4 actually measures approximately 1.5" × 3.5". This calculator uses nominal dimensions for consistency with lumber yard pricing.
Waste Factor
Always add a waste factor to account for cuts, defects, and mistakes. Standard recommendations are 5-10% for framing, 10-15% for decking, and 15-20% for flooring. This ensures you have enough material without ordering excess.
Project Type Guidelines
Decking Projects
Typical deck boards are 5/4×6 or 2×6, laid with 1/8" to 1/4" spacing for drainage and expansion. Standard joist spacing is 16" on center.
Flooring Projects
Hardwood flooring typically uses 3/4" thick boards in various widths. Tongue-and-groove boards fit tightly together with minimal spacing.
Framing Projects
Wall studs are typically 2×4 or 2×6, spaced 16" or 24" on center. Always include extra studs for corners, door/window openings, and plates.
Frequently Asked Questions
How do I calculate board feet?
Board feet = (thickness in inches × width in inches × length in feet) ÷ 12. For example, a 2×4 that's 8 feet long = (2 × 4 × 8) ÷ 12 = 5.33 board feet.
Why is waste factor important?
Waste factor accounts for cuts, mistakes, defects in lumber, and pattern matching. Without it, you'll likely run short and need to make additional trips to the lumber yard, potentially with different lot numbers that may not match exactly.
What's the difference between nominal and actual lumber sizes?
Nominal size is how lumber is sold (like 2×4), while actual size is the real dimensions after drying and planing (1.5" × 3.5"). The difference is due to the milling process. Always use nominal sizes when ordering lumber.
Can I use this calculator for treated lumber?
Yes! This calculator works for any type of lumber including pressure-treated, cedar, redwood, or composite decking. Just enter the dimensions and pricing for your specific material.