Over the years, audiences have watched Iain Armitage, star of “Young Sheldon,” grow up right before their eyes, sparking plenty of discussion about his noticeable growth spurt. The series premiered in September 2017 with Sheldon Cooper depicted as a 9-year-old. At that time, Armitage, who was the same age, was the perfect choice to portray the childhood version of the character from “The Big Bang Theory.” During the first season, Armitage shared a snapshot on X (formerly known as Twitter), featuring himself alongside co-stars Montana Jordan and Raegan Revord, posing in front of a growth chart. Posted in April 2018, the photo showed him at a modest height of 4 feet, 4 inches.
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As “Young Sheldon” continued, Armitage’s height kept pace with his character’s growth. By the final season’s debut in February 2024, Sheldon had reached 14 years of age. Naturally, both the character and Armitage, who was then 16, had grown from a child into a young adult. Many viewers saw Armitage as an ideal match for a young Jim Parsons, the original Sheldon on “The Big Bang Theory.” One fan commented on Reddit, noting, “Sheldon grew so tall especially in the last seasons […] it really lines up with how tall he is in ‘TBBT.'” Armitage now stands at 5 feet, 10 inches, just a few inches less than Parsons’ 6-foot-1 stature.
As the series progressed, so did Armitage’s notches on the growth chart. When the final season of “Young Sheldon” started airing in February 2024, Sheldon’s character was 14 years old. Obviously, both the character and the actor portraying him would have grown significantly since the early seasons. Armitage, 16 years old at the time, had gone from a child to a young man. Viewers noted that Armitage playing a young Jim Parsons — the actor who originally played Sheldon on “The Big Bang Theory” — was a perfect choice to fill the actor’s shoes. “Sheldon grew so tall especially in the last seasons […] it really lines up with how tall he is in ‘TBBT,’” a fan wrote in a Reddit post around the time the final episodes aired. Armitage is listed as standing 5 feet, 10 inches tall, which is just a few inches shorter than Parsons’ 6-feet, 1-inch build.
Fans swooned over Iain Armitage’s grown up pics
Even after “Young Sheldon” concluded, Armitage’s evolution continued. He returned to CBS with a guest role on “Ghosts” in April 2026. Reflecting on his career, Armitage expressed excitement about exploring roles beyond Sheldon Cooper. “Because I started doing this when I was so young, I have a lot of people that will come to me and tell me, ‘You look so different,'” he shared with Us Weekly. While eager to pursue new opportunities as he outgrows the character, Armitage still cherishes the bond with fans who recognize him as Young Sheldon.
The following year, fans could see just how much Armitage had grown since the series’ early days. Not long after turning 17 years old, the “Young Sheldon” alum uploaded two selfies to Instagram in which he wore glasses and struck Blue Steel-type poses that gave him a mature air. Followers popped up in the replies to comment on how much Armitage had changed. “You’re growing up too fast [Kleenex emoji] just the other day you went to school in a bow tie,” one wrote. “Gosh, I almost didn’t recognize him. He’s quite handsome,” another user commented about the glow-up.
Armitage’s transformation continued after “Young Sheldon” ended, as he returned to CBS for a guest appearance on “Ghosts” in April 2026. Afterward, Armitage spoke about how he looked forward to trying other roles different from Sheldon Cooper. “Because I started doing this when I was so young, I have a lot of people that will come to me and tell me, ‘You look so different,’” he told Us Weekly. Armitage did mention that while he was happy to move on as he aged out of the role, he still embraced fans knowing him as Young Sheldon.