Lumber dimensions: nominal vs actual
Dimensional lumber is smaller than its name: subtract 1/2 in from nominal sizes up to 6 in and 3/4 in from 8 in and larger (a 2×8 is 1 1/2 × 7 1/4 in).
| Nominal | Actual (in) | Actual (mm) |
|---|---|---|
| 1 × 2 | 3/4 in × 1 1/2 in | 19 × 38 mm |
| 1 × 3 | 3/4 in × 2 1/2 in | 19 × 64 mm |
| 1 × 4 | 3/4 in × 3 1/2 in | 19 × 89 mm |
| 1 × 6 | 3/4 in × 5 1/2 in | 19 × 140 mm |
| 1 × 8 | 3/4 in × 7 1/4 in | 19 × 184 mm |
| 1 × 10 | 3/4 in × 9 1/4 in | 19 × 235 mm |
| 1 × 12 | 3/4 in × 11 1/4 in | 19 × 286 mm |
| 2 × 2 | 1 1/2 in × 1 1/2 in | 38 × 38 mm |
| 2 × 3 | 1 1/2 in × 2 1/2 in | 38 × 64 mm |
| 2 × 4 | 1 1/2 in × 3 1/2 in | 38 × 89 mm |
| 2 × 6 | 1 1/2 in × 5 1/2 in | 38 × 140 mm |
| 2 × 8 | 1 1/2 in × 7 1/4 in | 38 × 184 mm |
| 2 × 10 | 1 1/2 in × 9 1/4 in | 38 × 235 mm |
| 2 × 12 | 1 1/2 in × 11 1/4 in | 38 × 286 mm |
| 4 × 4 | 3 1/2 in × 3 1/2 in | 89 × 89 mm |
| 4 × 6 | 3 1/2 in × 5 1/2 in | 89 × 140 mm |
| 6 × 6 | 5 1/2 in × 5 1/2 in | 140 × 140 mm |
Questions people ask
What size is a 4×4 really?
3 1/2 × 3 1/2 in (89 × 89 mm).
Related sizes
Sources and method
- American Softwood Lumber Standard, NIST PS 20
Imperial and metric values are converted with 1 in = 25.4 mm exactly and rounded only for display. Found a mistake? Report it and we will correct the page.