Common Lumber Dimensions
Nominal vs. actual lumber dimensions:
Why a 2" × 4" is not always a 2" × 4"
Lumber sizes are usually given in "nominal" measurements. The nominal measurements are a board's size before it has been planed smooth (surfaced) on all 4 sides. The actual measurements are the final size. If your project calls for precise measurements, be sure to check your lumber before purchasing.
Dimensional Lumber
| Nominal Size |
Actual Size |
| 1×2 |
3/4" × 1-1/2" |
| 1×3 |
3/4" × 2-1/2" |
| 1×4 |
3/4" × 3-1/2" |
| 1×6 |
3/4" × 5-1/2" |
| 1×8 |
3/4" × 7-1/4" |
| 1×10 |
3/4" × 9-1/4" |
| 1×12 |
3/4" × 11-1/4" |
| 2×2 |
1-1/2" × 1-1/2" |
| 2×3 |
1-1/2" × 2-1/2" |
| 2×4 |
1-1/2" × 3-1/2" |
| 2×6 |
1-1/2" × 5-1/2" |
| 2×8 |
1-1/2" × 7-1/4" |
| 2×10 |
1-1/2" × 9-1/4" |
| 2×12 |
1-1/2" × 11-1/4" |
| 4×4 |
3-1/2" × 3-1/2" |
| 4×6 |
3-1/2" × 5-1/2" |
| 6×6 |
5-1/2" × 5-1/2" |
Decking Planks
| Nominal Size |
Actual Size |
| 5/4 × 6 |
1" × 5-1/2" |
| 6/4 × 6 |
1-5/16" × 5-1/2" |