This week, the Internet caught fire with the unveiling of How Old Do I Look?Ā (found at How-Old.net), a new tool from Microsoft that tells you exactly what its name promises, as well as your gender. Just upload a photo of your face, and voila! Your whole day is ruined.

Hollywood is notorious for taking liberties with the ages of its actors, particularly when finding talent to play teenagers. The only way the cast ofĀ Grease could have plausibly attended Rydell High School is if every single student had been held back for about a decade.

But we were pleasantly surprised to discover that #HowOldRobot will not be seducedĀ by show business smoke and mirrors.Ā If anything, How-Old.net guesses that the overgrown high schoolers we see on screen areĀ even older than they actually are ā€” with the notable exception of perma-teen actress Bianca Lawson, who has been mathematically confirmed to be aging in reverse.

Alan Ruck as Cameron inĀ Ferris Bueller's Day Off

Real age: 30
Character'sĀ age: 18
#HowOldRobot age: 27

how-old.net

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Stockard Channing as Rizzo inĀ Grease

Real age: 33
Character'sĀ age: 18
#HowOldRobot age: 34

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Michael J. Fox as Marty McFly inĀ Back to the Future

Real age: 24
Character'sĀ age: 17
#HowOldRobot age: 41

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Jennifer Grey as Jeanie in Ferris Bueller's Day Off

Real age: 26
Character'sĀ age: 16
#HowOldRobot age: 32

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Tobey Maguire as Peter Parker inĀ Spider-Man

Real age: 27
Character'sĀ age: 18
#HowOldRobot age: 27

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Gabrielle Carteris as Andrea inĀ Beverly Hills,Ā 90210

Real age: 29
Character'sĀ age: 16
#HowOldRobot age: 41

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Rachel McAdams as Regina George inĀ Mean Girls

Real age: 25
Character'sĀ age: 16
#HowOldRobot age: 29

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Henry Winkler as Fonzie inĀ Happy Days

Real age: 29
Character'sĀ age: 19
#HowOldRobot age: 38

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Bianca Lawson as Megan inĀ Saved by the Bell: The New Class

Real age: 14
Character'sĀ age: 14
#HowOldRobot age: 35

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Bianca Lawson as Kendra inĀ Buffy the Vampire Slayer

Real age: 18
Character's age: Late teens
#HowOldRobot age: 27

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Bianca Lawson as Maya inĀ Pretty Little Liars

Real age: 33
Character'sĀ age: 17
#HowOldRobot age: 22

how-old.net

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Molly Fitzpatrick is senior editor of Fusion's Pop & Culture section. Her interests include movies about movies, TV shows about TV shows, and movies about TV shows, but not so much TV shows about movies.