Amp Breaker

Here's one that might have had a web based calculator when I first bookmarked it.
https://www.wiresizer.com/
A lot of info at
https://www.bluesea.com/support/art...oosing_the_Correct_Wire_Size_for_a_DC_Circuit
This is more for figuring out the wire size
https://www.wirebarn.com/Wire-Size-Calculator-_ep_41.html