We usually need four parameters to describe a paper roll size: width, diameter, length, and core. Paper roll sizes can be described in the following formats:

• width x diameter x core
• width x length x core

Here are some examples:

• For the paper roll size 80mm x 70mm x 13mm, where 80mm represents the paper width, 70mm represents the paper roll diameter, and 13mm represents the core size.
• In the case of the paper roll size 3 1/8″ x 230′ x 7/16″, the paper roll width is 3 1/8″, the paper length is 230′, and the core size is 7/16″

You can read this article if you’re interested in learning more about paper roll sizes. Additionally, you can refer to this link for information on the mathematical relationship between a paper roll’s diameter and length.