For example: with the waist circumference of 92 (cm) men belt size is 90.
Most of the times belts are marked with the numbers from 70 up to 120 with the interval of 5 units.
Belts size marking varieties:
There is also another way in marking belts size, for example, instead of waist circumference the belt length is shown. In order to determine Your belt size in this case You should add 15 (cm) to Your measures, and the obtained length would be the most suitable.
For example: with the waist circumference = 93 (cm) the belt size would be 108 (cm), that corresponds to the clothes size 52.
In American system the belts sizes depend on the sizes of jeans. If the belt is designed for jeans size 34, then this belt size would be 2 units bigger, that is 36.
As American manufacturers use alphabetic size marking, the belt from the above example would have letter M (36-38) on it.
Therefore, in order to find Your size the corresponding size chart should be used, by which, for the provided example, WC = 95±4 (cm).