We know that
The background story arc of "Lazarus Pit" takes place 30 years before the time of Batman Begins.
The time difference between Batman Begins and The Dark Knight must be approximately 6 months to a year.
Time difference between Dark Knight and The Dark Knight Rises is 8 years
In a backstory, we are revealed that Bane was the one who helped Talia Al Ghul to escape the lazarus pit. We are not shown his face but according to his physique he should have been between 18 to 20.
And regarding to this calculation, Bane must be 55+
38 [Time of Dark Knight Trilogy story arc] + 18 [youngest possible age of bane at the time of backstory]..
Is this assumption true?