Generated voltage formula

I am trying to construct a little permanent magnet generator. I would like to get a bearing on what kind of voltage I could get out of it based on the Gauss of the permanent magnets, distance from cores, rpm, etc. Or if anyone knows of a formula or a little calculator that does something similar or even an example. Thanks guys.

This https://www.otherpower.com/hamster.html unconventional link might help a lot.