User blog comment:Merganafan23/Character ages/timeline/@comment-24492510-20141106190737

In Series 2 Morgause is the oldest, because she is around 30 (she remembered Ygraine), Arthur is 21, Morgana is 19 and Merlin is 18-19 (depending on his actual birthday).

Morgana is confirmed to be Merlino's age.