The core kid characters in Stranger Things start out around age 12 in season 1 and are mid-teens by the later seasons.

Ages in the show

• In season 1 (set in 1983), Mike, Eleven, Will, Lucas, Dustin, and later Max are written as about 12 years old.

• By season 4, the same group is in high school and generally portrayed as about 14–15 years old in the story.

• Erica Sinclair is younger, starting around 9 in her early appearances and reaching about 11–12 by the more recent seasons.

Ages of the actors (approx.)

• When the show began, the main kid actors (Millie Bobby Brown, Finn Wolfhard, Gaten Matarazzo, Caleb McLaughlin, Noah Schnapp) were about 11–14 years old, roughly matching their characters.

• By the time of the later seasons, those actors are in their late teens to early twenties, several years older than the characters they are playing.

Character vs. actor ages

Character (S4–5 era)| Character age in story| Actor age around that time
---|---|---
Eleven| About 14–16| About 16–18+ years old 59
Mike, Will, Lucas, Dustin| About 14–16| Roughly 15–19+ years old 4810
Max| About 14–16| Around 17–20+ years old 15
Erica| About 11–12| Mid-teens in real life 35