6×6 Lumber actual size- (Explained)

Actual dimensions of 6 x 6 lumber are 5-1/2″ x 5-1/2″ (139.7 x 139.7 mm). In fact, it’s smaller than what the nominal measurements indicate.

Nevertheless, hardware stores call it 6-by-6 lumber despite the incorrect nominal size due to the standard measurement.

However, technically the size of 6×6 is correct as it was measured before the lumber gets through a planer to create uniform surfaces. As a matter of fact, hardware stores sell lumber with uniform surfaces but their measurement is according to the original dimensions.

A 6×6 board has the same length 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.  

6×6  lumber dimensions

6×6  lumberNominal size in inches Actual size in inches
6 Width5-1/2
6 height5-1/2
6×6  LumberNominal size in mmActual size in mm

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