Wednesday is 15 years old when season 1 begins and turns 16 during the events of the season.

In the show, Wednesday arrives at Nevermore Academy as a high-school sophomore, which typically aligns with being about 15 in the U.S. school system. During season 1, she celebrates her 16th birthday on October 13, confirming that she crosses from 15 to 16 within that first season’s timeline.