Lumber Sizes & Grades
Understanding lumber dimensions and quality standards
Understanding Lumber Sizes
Lumber is sold in nominal sizes, which differ from the actual dimensions. The difference accounts for drying and surfacing (planing) that occurs during manufacturing.
Common Dimensional Lumber Sizes
| Nominal Size | Actual Size | Common Uses |
|---|---|---|
| 1x4 | 3/4" x 3-1/2" | Trim, furring |
| 1x6 | 3/4" x 5-1/2" | Trim, shelving |
| 2x4 | 1-1/2" x 3-1/2" | Framing, studs |
| 2x6 | 1-1/2" x 5-1/2" | Joists, decking |
| 2x8 | 1-1/2" x 7-1/4" | Joists, beams |
| 2x10 | 1-1/2" x 9-1/4" | Joists, beams |
| 2x12 | 1-1/2" x 11-1/4" | Joists, headers |
| 4x4 | 3-1/2" x 3-1/2" | Posts |
| 6x6 | 5-1/2" x 5-1/2" | Posts, beams |
Lumber Grades
Lumber is graded based on appearance, strength, and intended use. Understanding grades helps you select the right material for your project.
Appearance Grades (Hardwood)
FAS (First and Seconds)
Highest grade, 83% clear on worst face
Select
Good one face, 83% clear
No. 1 Common
66% clear, some defects allowed
No. 2 Common
50% clear, more defects
Structural Grades (Softwood)
Select Structural
Highest strength, minimal defects
No. 1 & Better
High strength, good appearance
No. 2
Most common framing grade
No. 3 / Stud
Economy grade, vertical use only