In short, you should have one aim you use as a base for every game you play. Say you have a sensitivity in CSGO you are comfortable with, use this for all conversions.
When converting to a game you can choose between three methods:
360 Distance - Directly converts the distance needed to move the mouse to turn 360 degrees between the two games/aims. This only makes sense in the FOV is very close.
Monitor Distance - Matches the movement to a certain point on the monitor between the two aims. If the FOV is different, you can only perfectly match to one specific point.
Viewspeed - Think of this as an automatic Monitor Distance method, where the chord length is used as a constant. This usually falls in the 60-70% Monitor Distance range, and I would suggest trying this method first.
Also check out these two videos. They are of the old version of the calculator, but other than the new conversion method Viewspeed they are still valid. And incidentally shows an example on how to convert between the three games you play