I tried to google for it , but didnt find any good equation for this...
Like lets say preflop A opens 3bb, B 3bets to 9bb, C 4bets... what is the smallest ammount C is allowed to 4bet?
Is equation same for postflop minimal bets?

A lot of player including myself call raise to 2x a minraise, but i know its not right, and that minraise is always less than 2x, but not sure how its counted..