The actual size of 1 x 10 lumber is around 3/4″ x 9 1/4 inches (19 x 234.95mm). Definitely, it’s smaller than the nominal size but is the true size. However, despite the nominal size being incorrect, it is still referred to as 1-by-10 lumber in hardware stores due to the standard of measurement.
Home Depot and other local hardware stores sell 1×10 lumber that has smoothed and planned edges. So, Even though the measurement of 1×10 lumber seems inaccurate, which is 3/4 x 9 ¼ when you measure using a tape, technically it is correct.
The length of a 1×10 board remains the same regardless of whether it is nominal or actual. For example, if the nominal length of 1×10 is 10 feet, the actual length will be 10 feet.
Similarly, if the nominal length is 10 feet then the actual length would be 10 feet, and so a 12 feet length board will actually be 12 feet long, the same as the nominal length.
However, it’s better to do some quick measurements to find out the exact length.
1×10 lumber dimensions (Actual vs Nominal)
| 1×10 lumber | Nominal size in inches | Actual size in inches |
| Width | 1 Width | 3/4 |
| Height | 10 length | 9 1/4 |
| 1×10 Lumber | Nominal size in mm | Actual size in mm |
| Width | 25.4 | 19.05 |
| Height | 254 | 234.95 |
