The actual size of 2×6 lumber is 1 ½ x 5 ½ (38 x 140 mm), smaller than what is being advertised in hardware stores. The reason for this is that hardware stores sell lumber that has been planned. And the measurement of the lumber is taken when it was freshly cut.
The hardware store sells lumber in two sizes: Nominal size refers to the dimensions of the lumber before it’s smoothed for all sides. The actual size of a board is determined after it has been measured after planning. Even though the lumber’s dimensions have decreased, they still refer to them as their original measurements.
Since 2×6 lumber at hardware stores is usually a little smaller than advertised, measure it carefully to ensure that you get the right 2×6 lumber for your project.
2×6 lumber Length
There is no difference in the length of a 2×6 board whether it is nominal or actual.
A 2×6 will have an actual length of 6 feet if its nominal length is 6 feet. The length of a nominally lengthened board of 12 feet will actually be 12 feet.
2×6 lumber dimensions
| 2×6 lumber | Nominal size in inches | Actual size in inches |
| 2 | 1 ½ | |
| 6 | 5 ½ |
| 2×6 Lumber | Nominal size in mm | Actual size in mm |
| 50.8 | 38 | |
| 152.4 | 76.2 mm |
Why is the actual size of a 2×6 lumber smaller than its nominal size?
Generally, plans are measured after they have been rough sawn into their original shape. Afterward, hardware stores treat the lumber to make it smooth from all sides.
Through the planning process, the surface of the wood is smoothed to create a uniform thickness. During planning, thin layers of timber are sliced off from each side of the timber, causing its thickness to shrink. The result is that timbers with four-sided smooth surfaces lose both thickness and width, reducing their actual dimensions.
