Convert nominal to actual lumber dimensions
Lumber dimensions can be confusing. A "2x4" doesn't measure 2"x4" when you get it home. Here's why:
When lumber is first sawn, it is the nominal size. But during drying and planing, it shrinks and gets smoothed, resulting in smaller actual dimensions.
| Nominal | Actual |
|---|---|
| 1x2 | 3/4" x 1-1/2" |
| 2x4 | 1-1/2" x 3-1/2" |
| 2x6 | 1-1/2" x 5-1/2" |
| 4x4 | 3-1/2" x 3-1/2" |