Common actual lumber dimensions
| Nominal | Actual dry dressed | Metric |
|---|---|---|
| 1×2 | 0.75 × 1.5 in | 19 × 38 mm |
| 1×3 | 0.75 × 2.5 in | 19 × 64 mm |
| 1×4 | 0.75 × 3.5 in | 19 × 89 mm |
| 1×6 | 0.75 × 5.5 in | 19 × 140 mm |
| 1×8 | 0.75 × 7.25 in | 19 × 184 mm |
| 1×10 | 0.75 × 9.25 in | 19 × 235 mm |
| 1×12 | 0.75 × 11.25 in | 19 × 286 mm |
| 2×2 | 1.5 × 1.5 in | 38 × 38 mm |
| 2×3 | 1.5 × 2.5 in | 38 × 64 mm |
| 2×4 | 1.5 × 3.5 in | 38 × 89 mm |
| 2×6 | 1.5 × 5.5 in | 38 × 140 mm |
| 2×8 | 1.5 × 7.25 in | 38 × 184 mm |
| 2×10 | 1.5 × 9.25 in | 38 × 235 mm |
| 2×12 | 1.5 × 11.25 in | 38 × 286 mm |
| 4×4 | 3.5 × 3.5 in | 89 × 89 mm |
| 4×6 | 3.5 × 5.5 in | 89 × 140 mm |
| 6×6 | 5.5 × 5.5 in | 140 × 140 mm |
Why the name is larger than the board
Nominal lumber names describe a trade size, while the board is surfaced after initial sawing and loses dimension during drying and dressing. Current PS 20-25 publishes minimum dressed dimensions for dry and green softwood lumber. Moisture and permitted tolerances mean a real board should still be measured when fit is critical.
Read the nominal vs. actual guide or use the lumber weight calculator to apply these actual dimensions.