Hinges and Hardware 101 - Pin and Barrel Diameter

The pin and barrel dimension for a hinge can sometimes be a mistakenly called out, which at times can be confusing. They are related, but they are two separate dimensions as shown in this picture. The actual pin is one diameter, and then the barrel dimension (A) is basically the pin diameter (B) plus two times the material thickness. It's not equal to it, just due to the space required for the pin to move within the hinge, but for barrel dimension purposes, it will be within reasonable tolerances on most drawings. Sometimes people will confuse the two and say the barrel dimension instead of the actual pin dimension, but you can sometimes tell something is wrong because the "pin" dimension turns out to be three times or more the material thickness and that's not the norm. Check out more on the anatomy of a hinge here.