How do the levels scale between stars?

I heard that a 1* character at 40 is stronger than a 2 or 3* one. Does anyone know how they scale? At what point is a 3* equal to a lvl 85 2* character.

In terms of hp, match damage, and ability damage, I think its roughly around lvl 90-95.

A 3* hero at level 100 is roughly the same as a 2* hero at level 85 in raw stats. Their abilities, of course, may vary significantly.