I knew it was 50 buy ins of the selected tournament you wanted to play , but if you want to have a more strict bankroll , cause it's tournament play and it has a lot of variance , use the 100 buy ins rule for every tournament , its better .If you don't have the money , play a cheaper tour.
For cash games I think you should have a bankroll of 20xthe maximum amount of $ you buy on a session ,so if you play a 0.02-0,05 nl ZOOM with buins 2.5$ min 5$ max you must have 100$ bankroll , if you don't have 100$ and you have 80$ you play a 0.01-0.02 with buy ins 1$ and2$ and bankroll required 2$(x)20=40$only. (I prefer x30 so x30themaxbuin is better , use it ).all these for the no limit cash games .
For limit cash games I think you have to got 400 Bb at least before you enter the game
.