The actual dimensions of 1 x 2 lumber are 3/4 x 1 1/2 inches (19 x 38 mm). Despite the incorrect nominal size, hardware stores still refer to this lumber as 1-by-2. Actually, hardware stores sell treated and planned lumber that has been shrunk from its original dimensions.
The size of 1×2 lumbers on stores is determined when the surfaces are sanded to make the surface smooth, and lighter by reducing the moisture content of the wood. Consequently, a 1×2 lumber’s nominal size is incorrect, although technically the lumber was of the same size at the time of its sawing.
However, The length remains the same as 1×2 regardless of its actual or nominal size. For example, an 8 feet long board will have an 8 feet actual length, the same is true with other sizes such as 6 feet, 10 feet, 4 feet, etc.
In order to find out the exact dimensions, it’s best to do some quick measurements.
1×2 lumber dimensions
| 1×2 lumber | Nominal size in inches | Actual size in inches |
| Width | 1 Width | 3/4 |
| Height | 2 length | 1/2 |
| 1×2 Lumber | Nominal size in mm | Actual size in mm |
| Width | 25.4 | 19.05 |
| Height | 50.8 | 38 |
Why is the actual size of a 1 x 2 lumber smaller than its nominal size?
Typically, a plank is measured as it is in its original shape, but the lumber we purchase has been smoothened during the manufacturing process. This process results in the board shrinking.
