I\'m working on a project that lets users track different data types over time. Part of the base idea is that a user should be able to enter data using any units that they n
Thought to mention the units package which is part of the Astropy package.
It's well maintained, easy to use, and has all the basic units (as well as astrophysics-related units).
It provides tools for both units and quantities. And there's also a module for physical constants.