Question: is a 2x4 actually 2x4?
Answer: In the past, when a timber was called a 2x4 [or "two-by-four"], it actually measured 2 inches by 4 inches. Now, most timber is milled and planed to give it a little more of a finished look, and a little more of a consistent size and profile. ... Instead, a 2x4 is really only 1 1/2" by 3 1/2". The same is true of pine.