The majority of bearings have only 3 separate dimensions; inside diameter, outside diameter and width. These dimensions can be measured using vernier calipers, tape measure or a ruler (calipers preferred for accurate measurements).
Inside Diameter:
The inside diameter is measured by inserting the out anvils into the center of the bearing and opening the calipers until contact is made on either side. Try and ensure that the calipers are open as wide as possible for an accurate measurement.
Outside Diameter:
The outside diameter of a bearing is measured by