What is the actual measurement of a 2 by 4 board?

A 2 by 4 board is referred to by its nominal size, which is a way of describing the dimensions as measured before the wood is planed and dried. When you buy a board labeled as "2 by 4," the actual dimensions of the board are 1.5 inches by 3.5 inches. This reduction in size occurs due to the milling process, which smooths the board and removes wood to achieve a specific shape and finish.

In practical use within technical theatre, where precise measurements are crucial for building sets and structures, it’s important to understand that the dimensions you see on the label are not the actual dimensions after processing. Recognizing this aids in accurately planning and constructing any elements required for productions, ensuring the pieces fit together as intended.