The dimension of an O-ring is defined by its inner diameter and its cord thickness. In principle, it is possible to produce almost any O-ring size.
However, as this is not an efficient solution on a national and especially global level, dimensional standards for O-rings have been introduced to the market.
Important to know: A basic distinction is made between inch and metric dimensions.
Inch dimensions have their origins in the imperial system of measurement, which originated in England. However, since the rest of the world finds it difficult to calculate in “inches”, there is a conversion from the unit “inch” to the metric unit “mm” in every list of standards.
Example: 0.801 x 0.07 inch = 20.35 x 1.78 mm
Metric dimensions, on the other hand, are always given in the metric unit “mm”.