How is dimensional lumber measured?
Dimensional lumber is cut to standard thicknesses and widths. Dimensional lumber is the actual size of the board but the nominal dimension is the size we see printed or labeled on the wood. In other words, we’re buying a nominal size 2×4 board but the dimensional or actual size is 1-½ inches by 3-½ inches.
Why isn’t a 2×4 actually 2×4?
DIMENSIONAL LUMBER: In the past, when a timber was called a 2×4 [or “two-by-four”], it actually measured 2 inches by 4 inches. Because of this extra milling, a 2×4 no longer measures a full 2 inches by four inches. Instead, a 2×4 is really only 1 1/2″ by 3 1/2″. The same is true of pine.
Why is a 2×4 actually 1.5×3 5?
The 2×4 refers to the rough-cut green wood: it shrinks during drying, then the dried wood is planed smooth, so the finished lumber is supposed to end up at 1.5″x3. 5″. While it doesn’t really shrink that much, the mills get more usable finished 2×4’s from a given tree if they cut them slightly smaller to begin with.
What does a 1×8 measure?
Common Lumber Dimensions
| Nominal Size | Actual Size |
|---|---|
| 1×6 | 3/4″ x 5-1/2″ |
| 1×8 | 3/4″ x 7-1/4″ |
| 1×10 | 3/4″ x 9-1/4″ |
| 1×12 | 3/4″ x 11-1/4″ |
How big is a 2×4 actually?
A piece of surfaced (sanded smooth) 2×4 lumber actually measures 1½ inches thick and 3½ inches wide. In rough-cut condition, a 2×4 is slightly less than 2 inches thick and approximately 4 inches wide. When wood is milled from a rough to a smooth surface, it loses about ¼-inch from each of its four sides.
When did they stop making real 2×4?
This pressured further compromise because thinner 2x4s were a way to compete in price with wood alternatives. Size standards, maximum moisture content, and nomenclature were agreed upon only as recently as 1964. The nominal 2×4 thus became the actual 1½ x 3½, imperceptibly, a fraction of an inch at a time.
