User blog comment:Emily Windsnap/How old are the Merlin characters?/@comment-86.143.248.83-20150223031652

In Series 1 Merlin is 17 years old while Arthur's about 17-18 years old. Morgana is a year - or two - older than Arthur so she'd be about 19-2o years old while Gwen is the same ages as Arthur. When Mordred first appears he's about 12-13 years old. Since each Series is set a year apart - 3 years between Series 4 & 5 - Merlin should be 20 years old in Series 4 & 23 in Series 5. Arthur & Gwen should be 20-21 in Series 4 & 23-24 in Series 5. Morgana should be 22-23 in Series 4 & 25-26 in Series 5. Mordred should be 18-19 in Series 5.

The knights are in their late 20s-early 30s in Series 4-5 but since Leon's the eldest he's probably in his 30s in the Merlin series.