Board Thread:Character Discussion/@comment-26062156-20150131174600/@comment-5925413-20150315191008

According to Jennifer Lee's tweets about Frozens headcanons, Anna was born on a 21st June for the summer solstice (and Elsa the winter one on the 21st December), and she was 19' on the coronation day that takes place in July.

Once Upon a Time s4A events ending in November (when the Mother Superior and the fairies vanished), and two years after the movie (and so before Ingrid freezes Arendelle for 30 years), Anna is 21.