What is the nominal size of a standard 2x4 lumber?

The nominal size of standard 2x4 lumber is 1.5 inches by 3.5 inches. This size reflects the actual dimensions of lumber after it has been dried and planed, which reduces its initial rough-cut dimensions. The term "nominal" refers to the name used to describe the lumber, which is based on its original dimensions before any processing.

When lumber is freshly cut, it may be referred to as 2 inches by 4 inches; however, the drying and planing processes shrink the dimensions. This allows for a more uniform and usable product. Therefore, when purchasing or using lumber, it's important to recognize that the nominal sizes are often different from their actual measurements, which is crucial for construction and design work. Understanding this distinction helps ensure proper planning and execution in building projects.