The two numbers used in international staple sizing are the gauge of the wire and the length of the staple shank, given in millimetres. A lower wire gauge number means a thicker staple, while a higher shank number means a longer leg.
The most widely recognised standard for staple sizes reads wire gauge/shank length, such as 23/8, for example, where the gauge of the wire (23) is the former, and the shank length (8 mm) is the latter. One example of an exception to this rule is the standardised size No. 10 staple, which is used for mini staplers.
Before purchasing staples, always check the stapler that will be used for a specific staple size that may be stamped inside the cover or on the base. If so, use the manufacturer’s recommendation for the best stapling performance.