What are the actual dimensions of a 2x4 piece of lumber?

The actual dimensions of a 2x4 piece of lumber are 1.5 inches by 3.5 inches. This size discrepancy arises from the manufacturing process, where dimensional lumber is cut to larger sizes initially, then dried and planed, which reduces its dimensions.

In the case of a nominal 2x4, when it is finished, it ends up being 1.5 inches thick and 3.5 inches wide. This standardization is crucial for builders and carpenters, as it ensures compatibility with other framing materials and components in construction. Understanding these actual dimensions is essential for accurate building, planning, and ensuring acceptable structural integrity in projects.