The main kids in Stranger Things start out around 12 years old in season 1, and by the final seasons their characters are mid‑teens while the actors themselves are now in their late teens to mid‑20s.

Core cast ages

Here’s a quick look at the key “kids” both as characters on the show (latest seasons) and roughly how old the actors are now (early 2026), based on recent entertainment coverage and official breakdowns.

  • Eleven (Millie Bobby Brown)
    • Character: About 12 in season 1, around 16 by season 5.
* Actor: Born February 19, 2004, so about 21 now.
  • Mike Wheeler (Finn Wolfhard)
    • Character: About 12 in season 1, mid‑teens (around 16) by season 5.
* Actor: Mid‑20s in 2026 (early 20s as of late‑2025 reports).
  • Will Byers (Noah Schnapp)
    • Character: About 12 at the start, around 16 in the latest season.
* Actor: Youngest of the original boy group; around 21 now.
  • Lucas Sinclair (Caleb McLaughlin)
    • Character: Also about 12 in season 1, around 16 in season 5.
* Actor: Reported mid‑20s by 2025.
  • Dustin Henderson (Gaten Matarazzo)
    • Character: Roughly 12 in season 1, mid‑teens later on.
* Actor: Around early‑20s now according to recent age roundups.
  • Max Mayfield (Sadie Sink)
    • Character: Joins in season 2; about 13 then, around 16 by season 5.
* Actor: Early‑20s in the most recent coverage.
  • Erica Sinclair (Priah Ferguson)
    • Character: Younger middle‑schooler, about 9–11 in seasons 2–4 and early‑teens by season 5.
* Actor: Late‑teens/around 19 in recent reports.

Season‑by‑season vibe

  • In season 1 , the core kids’ characters are written as about 12‑year‑old middle‑schoolers.
  • By the latest season (5) , most of them are shown as 15–16‑year‑olds dealing with high‑school and more intense storylines.

So if you’re wondering “how old are the kids in Stranger Things?”: on screen they’re early‑teens at the start and mid‑teens by the end, while in real life the actors have grown into their late teens and 20s.