Nominal vs. Reality
Wood Dimensions
Measurements of Dimension Lumber
| Name | Size (in) | Size (mm) |
| 1 x 2 | 3/4 x 1 1/2 | 19 x 38 |
| 1 x 3 | 3/4 x 2 1/2 | 19 x 64 |
| 1 x 4 | 3/4 x 3 1/2 | 19 x 89 |
| 1 x 5 | 3/4 x 4 1/2 | 19 x 114 |
| 1x 6 | 3/4 x 5 1/2 | 19 x 140 |
| 1 x 8 | 3/4 x 7 1/4 | 19 x 184 |
| 1 x 10 | 3/4 x 9 1/4 | 19 x 235 |
| 1 x 12 | 3/4 x 11 1/4 | 19 x 286 |
| 2 x 2 | 1 1/2 x 1 1/2 | 38 x 38 |
| 2 x 3 | 1 1/2 x 2 1/2 | 38 x 64 |
| 2 x 4 | 1 1/2 x 3 1/2 | 38 x 89 |
| 2 x 6 | 1 1/2 x 5 1/2 | 38 x 140 |
| 2 x 8 | 1 1/2 x 7 1/4 | 38 x184 |
| 2 x 10 | 1 1/2 x 9 1/4 | 38 x235 |
| 2 x 12 | 1 1/2 x 11 1/4 | 38 x 286 |
| 4 x 4 | 3 1/2 x 3 1/2 | 89 x 89 |
| 4 x 6 | 3 1/2 x 5 1/2 | 89 x 140 |
| 6 x 6 | 5 1/2 x 5 1/2 | 140 x 140 |
Source: The Spruce Crafts
Hardwood Sizing
| Name | Surfaced 1 side (“S1S”) | Surfaced 2 sides (“S2S”) |
| 1/2 inch | 3/8 inch (9.5 mm) | 5 1/16 inch (7.9 mm) |
| 5/8 inch | 1/2 inch (13 mm) | 7/16 inch (11 mm) |
| 3/4 inch | 5/8 inch (16 mm) | 9/16 inch (14 mm) |
| 1 inch (or 4 quarters) | 7/8 inch (22 mm) | 13/16 inch (21 mm) |
| 1 1/4 inches (or 5 quarters) | 1 1/8 inches (29 mm) | 1 1/6 inches (27 mm) |
| 1 1/2 inches (or 6 quarters) | 1 3/8 inches (35 mm) | 1 5/16 inches 33 mm |
| 2 inches (or 8 quarters) | 1 13/16 inches (46 mm) | 1 3/4 inches (44 mm) |
| 3 inches (or 12 quarters) | 2 13/16 inches (71 mm) | 2 3/4 inches (70 mm) |
| 4 inches (or 16 quarters) | 3 13/16 inches (97 mm) | 3 3/4 inches (95 mm) |
Source: The Spruce Crafts
Plywood
| Name | Actual dimensions |
| 1/4 inch | 7/32 (5 mm) |
| 1/2 inch | 15/32 (12 mm) |
| 3/4 inch | 23/32 (18 mm) |
Source: The Spruce Crafts