User blog comment:Emily Windsnap/How old are the Merlin characters?/@comment-86.143.248.83-20150223031652/@comment-118.211.55.195-20170107160628

Not quite.

Arthur comes of age during series one - given the frequent mentions that the purge happened 20 years prior, that would make him 20 turning 21 in episode one, as it was his mother's death that started the purge, and 21 makes sense as a 'coming of age'.

Morgana is roughly Arthur's age, though given behaviour etc. is very likely a bit older. Perhaps 21-22. (There is a note in a script about her being around Merlin's age, but that could've been retconned, or just a generalisation. I'd say my sisters are around the same age despite there being a 2 year gap in age between them, for example).

There's no information on Gwen at all, except that it's implied she's younger than Morgana. I'd say she's of an age with Arthur.

Merlin has to be younger than Arthur - he was definitely conceived after the purge (including the time it took for Balinor to meet and become close with Hunith). It's also implied he turned 21 between series three and four. That would make him 16-18 during series one.

Mordred looked to be about 9 or 10 when we first meet him as a child.

The show takes place over a period of roughly 9 years given the gaps between seasons. That would make Arthur around 30, Morgana 32, Gwen perhaps 30 or 31, Merlin 25-27, and Mordred 18 or 19.