The Finest Quality Doors, Mouldings & Millwork

S4S Lumber Sizes

Nominal Versus Finished Sizes

2x4s are not actually 2 inches by 4 inches. When the board is first rough sawn from the log, it is a true 2×4, but the drying process and planing of the board reduce it to the finished 1.5×3.5 sizes. Here are the common sizes of lumber, and their actual sizes.

Note: S4S means surfaced four sides. Surfacing is most typically done by using a planer resulting in a wavy surface with several knife marks (see diagram on left) and the “S” does not stand for sanded. Here at NCWP, we do sand all 4 sides of our S4S product as well as the finished faces of all of our other millwork products.