When Eleven was first introduced on the show, we didn't know her exact age — only that her mother had been trying to find her for about 12 years.Now that about two years have passed, that would mean Eleven is approximately 14 years old.Like Eleven, Mike and his friends should all be just about 14 years old. They graduated from middle school between seasons two and three, and are now freshman in high school on Stranger Things season four.Of all the actors and their fictional counterparts, Schnapp used to be closest matched with his character. But now that we had a longer gap between seasons, Schnapp is a few years ahead of Will.Just like the rest of the friend group, Lucas is in his freshman year of high school on Stranger Things season four. McLaughlin was the first of his younger costars to get a driver's license, and now he's almost of legal drinking age.Erica is now in middle school, taking over the role of youngest nerd on Stranger Things now that the boys have aged up. Just like McLaughlin (who plays her on-screen love interest) Sink is a bit older than her other teen costars on Stranger Things.Once again, Dustin should be around 14 on the fourth season of Stranger Things as he heads into high school. But Matarazzo will turn 20 years old later this year, officially leaving his teenage years behind.Keery's character Steve has become friends with the younger teens on the show and looks after them. In real life, the actor is a decade older than all of his costars.Robin's character seems to be in her senior year of high school in season four, and would therefore be around 18 years old. Nancy is in her final year of high school, which means she's around 18 years old like Robin — about eight years younger than the actress in real life.Heaton and Dyer are dating in real life, just like their fictional counterparts on Stranger Things. Both characters are applying for colleges and getting ready to leave high school, which means they're around 18 years old.