Bane saved Talia when she was a baby. He was pretty old maybe in his 20s or 30s. But then she grows up and wouldn't that make Bane 60? He looks young.
Timeline Info from Script:
When Miranda Tate is introduced, the Script says she is in her 30s.
So the short answer is 20-29 years between Talia Al Ghul escaping the prison and the beginning of the events in The Dark Knight Rises.
Batman Begins Script info: Bruce Wayne is age 8 in the first scene where he falls into the cave.
Bruce Wayne is age 28 when he meets Ra's Al Ghul:
Bruce Wayne's 30th Birthday is at the end of Batman Begins:
Timeline Info from Movies:
Bruce Wayne spent 7 years traveling abroad according to Alfred in Batman Begins:[source]
In The Dark Knight,
I interpret this as one of two possibilities: 1) a year ago batman didn't exist; or 2) a year ago Bruce Wayne was just starting as Batman and had not yet dealt a crippling blow to their organization.
In The Dark Knight Rises,
So, The Dark Knight Rises takes place at least 9 years after Batman Begins.
So, from all of this: Between 20 and 29 years passed from the time Talia escaped to the events at the beginning of The Dark Knight Rises. Bane in the prison is at least in his late teens. All we see of him is a fairly young looking face.
So, we have a rough timeline. Assume year 0 is Bruce Wayne's birth. Years in italics, the specific year is unknown and provided as ranges which should contain all possible years, Years in bold are certain, and based on above sources. Any range (i.e. 0-9) indicates the exact point at which the event occurred is unknown, but could be anywhere in between, based on above sources.
0: Bruce Wayne Born.
So, based on that, there does seem to be an age problem. I don't think it was ever explicitly stated that Bane is younger than Bruce Wayne, just that Bruce Wayne was no longer in his top physical capability, being a recluse for 8 years and using a cane.
Timeline Info from Actors/Actresses age:
Bane was enhanced by Venom, giving him superhuman strength and an indestructible quality. There's no mention of this in The Dark Knight Rises, but I would suppose that there's few alternative ways he could survive the injuries he sustained in the Pit. He is probably much older than he appears because of the Venom.May be looks 20 years younger then
Borrowed answer from Scfi's Answer.
I think it's implied that Bane is older than Tom Hardy at the time (at least). I just get that impression about his character, the way he acts, the older tone of his voice and also during the fight scene, he criticizes how Batman "Fights like a younger man". It's inferred he's older, 40, or even more than 50 depending upon how old he's supposed to be in the pit scene.