Age is not considered. Much more important than age is experience. Meaning, if you're 32 and have only had 1 job for 1 year, you obviously won't be able to come in as a consultant.
That being said, the general age range is:
20-27: Entry level (i.e. Associate/Analyst)
25-32: Midrange (i.e. Consultant, Project Lead, etc)
29+: Higher level (Associate Partner, Partner)
Overlap is intentional :)