Fern from Frieren: Beyond Journey’s End is a human mage who is shown at several different ages throughout the story, ranging from a child to a young adult.

  • She first appears as a young girl around 8–9 years old when Heiter takes her in.
  • She is 13 years old shortly before Heiter’s death, during her early training with Frieren.
  • She turns 16 when Frieren gives her the butterfly hair clip she wears regularly.
  • During the journey and the First-Class Mage Exam arc, she is around 16–18 years old.
  • By the later parts of the story (towards the end of the currently adapted anime/manga events), she is generally described as being about 19–20 years old.

So, if you’re asking “how old is Fern (Frieren) now in the story?”, most sources group her main adventuring period as being in her late teens, roughly 16–18 , with some later material and overviews stating she eventually reaches about 19–20 years old as the timeline advances.