Board Foot Calculator
Calculate lumber volume in board feet for your projects
Board Foot Formulas
What is a Board Foot?
A board foot is the standard unit of measurement for lumber in North America. One board foot equals a piece of wood 1 inch thick, 12 inches wide, and 12 inches long—or 144 cubic inches of wood. It measures volume, not surface area.
Lumber is priced by the board foot ($/BF), which allows fair pricing regardless of board dimensions. Hardwoods are typically sold by the board foot, while dimensional softwoods (2x4s, etc.) are sold by the linear foot.
Understanding board feet helps you estimate project costs, compare lumber prices, and avoid overpaying. A 1-inch thick, 6-inch wide, 8-foot board contains 4 board feet.
Nominal vs Actual Dimensions
Nominal Size
What lumber is called (2x4, 1x6). Used for board foot calculation.
Actual Size
True dimensions after milling. A 2x4 is actually 1.5" × 3.5".
Rough Lumber
Sold at full nominal size (true 1" thick). Common for hardwoods.
S4S Lumber
Surfaced 4 sides. Loses 1/4" per side from nominal.
Common Lumber Prices (Approximate)
| Species | Grade | $/Board Foot | Notes |
|---|---|---|---|
| Pine (white) | Select | $3-5 | Softwood, common |
| Oak (red) | FAS | $6-10 | Popular hardwood |
| Maple (hard) | FAS | $7-12 | Durable, light color |
| Walnut | FAS | $10-18 | Premium, dark wood |
| Cherry | FAS | $8-14 | Ages beautifully |
| Cedar | #1 Common | $4-8 | Rot resistant, outdoor |
Tips for Buying Lumber
Calculate with Waste
Add 15-20% extra for waste from cuts, defects, and mistakes. Better to have extra than run short.
Inspect Before Buying
Check for warping, checking (cracks), knots, and moisture content. Hand-select when possible.
Buy Random Widths
Buying mixed width bundles is often cheaper per BF than specific widths.
Consider Local Mills
Local sawmills often beat big box store prices, especially for hardwoods.
Frequently Asked Questions
How do I calculate board feet?
Multiply thickness (inches) × width (inches) × length (feet), then divide by 12. Or use: T × W × L(inches) ÷ 144. A 1" × 6" × 8' board = (1 × 6 × 8) ÷ 12 = 4 board feet.
Why is lumber priced by the board foot?
Board feet normalize pricing across different sizes. A 1×12 and a 2×6 of the same length have the same board feet, so they cost the same for the same species and grade.
What does 4/4 lumber mean?
Hardwood thickness is stated in quarters of an inch. 4/4 = 1 inch, 5/4 = 1.25 inches, 6/4 = 1.5 inches, 8/4 = 2 inches. This is rough (pre-surfacing) thickness.
How much lumber do I need for my project?
List all parts with dimensions, calculate board feet for each, sum them up, then add 15-20% for waste. Group cuts to maximize efficiency from each board.
Pro Tips
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