Square tubing is typically available in dimensions ranging from 1/2 by 1/2 inch to 32 by 32 inches. The thickness of the tubes varies from 1/8 inch to 5/8 inches, and the tubes are available in standard lengths of 20, 24, 40 and 48 feet.
The dimensions of the square tubing refer to the outer width of the square. Tubes with dimensions of 1/2 by 1/2 inch to 1 by 1 inch come in size increments of 1/8 inch. From 1 1/4 to 2 inches, the tube size varies in increments of 1/4 inch, and from 2 1/2 to 5 1/2 inches, the tube sizes increase in increments of 1/2 inch. Tubes with dimensions above 5 1/2 inches are available in size increments of 1 or 2 inches.
Smaller square tubing has thinner walls, whereas the walls of larger tubes are thicker.