Common lumber sizes (nominal):
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What is a Board Foot?
A board foot (BF) is a unit of volume used for lumber. One board foot equals 144 cubic inches, or a piece of wood 12" × 12" × 1".
Board Feet Formula
Where thickness and width are in inches, and length is in feet.
Why Board Feet Matter
Hardwood and specialty lumber is priced per board foot. Understanding this measurement helps you compare prices and estimate project costs accurately.
Nominal vs Actual Lumber Sizes
Lumber is sold by nominal size, but actual dimensions are smaller due to drying and planing.
Common Conversions
- 2×4: Actual 1.5" × 3.5"
- 2×6: Actual 1.5" × 5.5"
- 2×8: Actual 1.5" × 7.25"
- 2×10: Actual 1.5" × 9.25"
- 2×12: Actual 1.5" × 11.25"
- 4×4: Actual 3.5" × 3.5"
- 1×6: Actual 0.75" × 5.5"
Frequently Asked Questions
Should I calculate with nominal or actual size?
For purchasing lumber, use nominal sizes. For calculating if lumber will fit your project, use actual dimensions.
How much extra lumber should I buy?
Plan for 10-15% waste for most projects. Lumber can have defects, knots, or warping that make some pieces unusable.
What's the difference between board feet and linear feet?
Linear feet measures length only. Board feet measures volume. A 2×4×8' is 8 linear feet but 5.33 board feet.