User blog comment:Emily Windsnap/How old are the Merlin characters?/@comment-4135736-20120504205021

I think by the time Series 1 started, Merlin was 18, Arthur was 21, Morgana was 20 (I'm not sure if she was older than Arthur) and Gwen was about 20. In Series 5 Merlin will be about 25, Arthur will be 28, Morgana will be 27 and same with Gwen while I bet Mordred will be 17 or 18 when he returns.