Understanding Wood Sizes

Why Doesn't a 2x4 Actually Measure 2-inches by 4-inches?

When visiting your local home center or lumber yard, you’ll notice that stock comes in varying wood sizes.

Additionally, softwood sizes differ from hardwood sizes. While the numbers may seem logical, they can be a bit deceiving, as you’ll soon discover.

Why one-inch isn't really one-inch:

Everybody has heard of a 2×4 (pronounced “two by four”), but few people realize that the actual height and width of a 2×4 is really somewhere close to 1 1/2″ x 3 1/2″ depending on dryness of the material and milling methods.

I know, it’s stupid. But hey, it is what it is. And if you don’t account for it when building, you will be fucked.

Similarly, a 1x (pronounced “one-by”) is only about 3/4″ in thickness. Wood shrinks when it is dried, so lumber mills adjust their tools accordingly.

Length of a piece of stock is not affected, so an 8′ 2×4 is usually very close or even slightly longer than 96-inches.

Softwood Sizing:

Most softwoods, used in home construction and for general purpose woodworking, come in 1x and 2x sizes.

Some columns display the “advertised sizes” and can be compared to the typical actual sizes in the corresponding columns. For instance, a 2×6 typically measures out at 1-1/2″ x 5-1/2″ in actual size.

Hardwood sizing: