4x4 Actual Size
Find the actual thickness, width, and metric dimensions of a standard 4x4 lumber post.
4x4 Actual Dimensions
| Measurement | Actual Size |
|---|---|
| Nominal Size | 4 × 4 inches |
| Actual Thickness | 3.5 inches |
| Actual Width | 3.5 inches |
| Metric Size | 89 × 89 mm |
What Is the Actual Size of a 4x4?
A commonly sold dry 4x4 board has an actual finished size of approximately 3.5 inches thick × 3.5 inches wide.
The name 4x4 refers to the nominal size of the lumber rather than its final finished dimensions.
Why Is a 4x4 Not Actually 4 by 4 Inches?
Lumber is typically cut larger than its final dimensions and then dried and surfaced. Planing and finishing reduce the dimensions, which is why a nominal 4x4 is commonly about 3.5 × 3.5 inches after finishing.
4x4 Size in Millimeters
The commonly referenced metric dimensions are approximately 89 × 89 mm.
Actual dimensions can vary depending on lumber grade, moisture condition, manufacturer, and product specifications.
Common Uses for 4x4 Lumber
4x4 lumber is commonly used for posts, supports, fence construction, deck structures, garden projects, and other construction applications.
Related Lumber Sizes
FAQ
How thick is a 4x4?
A commonly sold dry 4x4 is about 3.5 inches thick.
How wide is a 4x4?
A commonly sold dry 4x4 is about 3.5 inches wide.
What is a 4x4 in millimeters?
The commonly referenced metric size is approximately 89 × 89 mm.