User blog comment:Morganamagic7/Siblings Age/@comment-24492510-20141107165822

The ages are never officially released.

We know that around 3 and a half years passed from the start of Series 1 to the start of Series 4, because every series lasted around 6 months.

Arthur is 20 at the start of Series 1 and turns 21 in the ninth episode... and he is around 25 at the end of Series 4.

Morgana can't be 16, because it is clear that she is slightly younger than Arthur. Also, it is confirmed that she is around Merlin's age. Merlin was born to Balinor and Hunit. Balinor met Hunit after the Great Purge. So, Merlin was born at least after the Great Purge (11 months) + 9 months = 20 months. Also, Merlino is described as a young man in Series 4, so he is at least 2 and a half and not more than 3 and a half younger than Arthur. This means that Morgana is at least 17 (almost 18) in Series 1.

Morgause was at least 26-27 when she went to Camelot in Series 1, because she remembered Ygraine very well and people memory belongs at 5-6 years old.