The Ring Gasket is the possibly the most common shape of gasket. It is also the easiest to measure. Simply measure the diameter of the inside of the circle – also called and inside diameter or I.D. Then, measure the diameter the outside of the circle, also called the outside diameter- or O.D.

Dimensions needed to measure a Ring Gasket:

• Inside Diameter (I.D.)
• Outside Diameter (O.D.)

A full face or bolt hole gasket consists of five measurements. First, measure the Inside Dimension (I.D.) and Outside Dimension (O.D.) just like you would a ring gasket. Then, count the number of Bolt holes and also measure the diameter of the bolt holes. The final dimension is the Bolt Circle. The bolt circle is most difficult and confusing dimension to measure and understand for most people. It doesn’t have to be. The Bolt Circle is easily measured from the left side of one bolt hole to the left side of bolt hole across the diameter (bolt hole directly opposite it) or the right side of one bolt hole to the right side of bolt hole across the diameter (bolt hole directly opposite it).

Dimensions needed to measure a Full Face:

• ID
• OD
• Number of Bolt Holes
• Diameter of the Bolt Holes
• Bolt Circle