Question 1

What is nominal vs actual size?

Accepted Answer

Nominal size is the rough-cut dimension (e.g., 2×4), while actual size is the finished dimension after drying and planing (1.5" × 3.5" for a 2×4).

Question 2

How do I calculate board feet?

Accepted Answer

Board feet = (Thickness × Width × Length) / 144, where all measurements are in inches. For a 2" × 6" × 8' board: (2 × 6 × 96) / 144 = 8 board feet.

Question 3

Why are lumber sizes different from their names?

Accepted Answer

Lumber is named by its rough-cut size but sold at actual (finished) size. A 2×4 starts as 2"×4" rough-cut, but after drying and planing becomes 1.5"×3.5".

Question 4

What's the most common lumber mistake?

Accepted Answer

Assuming nominal dimensions are actual dimensions. Always use actual sizes for projects: a 2×4 is really 1.5"×3.5", a 1×6 is 0.75"×5.5".

Nominal to Actual size Lumber Calculator - Free Online Tool

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