Which material measurement is most common in thicknesses when discussing lumber?

When discussing lumber thickness, the most common measurement is in quarters of an inch. This unit allows for more precise communication regarding the thickness of lumber, especially since lumber is often sold in sizes that are nominal (the name reflects a rough measurement rather than the actual size).

For example, a 1x4 board is nominally referred to as being 1 inch thick and 4 inches wide, but its actual thickness is typically less than one inch due to the drying and planing processes it undergoes. Using quarters of an inch provides a convenient way to express these variations in thickness. For instance, if a board is 1¼ inches thick, it can be easily described as being 5 quarters.

In contrast, while millimeters are precise, they are less commonly used in the context of lumber in the United States, where imperial measurements prevail. Measuring in inches only is useful, but it lacks the precision offered by quarters of an inch when discussing the minor variations in lumber size. Feet is typically used for lengths rather than thickness, making it less relevant in this context. Thus, quarters of an inch remains the standard approach for illustrating the thickness of lumber in many woodworking and construction scenarios.