Gabe Duncan from 'Good Luck Charlie' is played by Bradley Steven Perry, and I’ve always been curious about his height too! From what I’ve gathered, he’s around 5'6" (feet and inches) as of his late teens during the show’s run. It’s funny how child actors grow up so fast—I remember watching the early seasons where he was this tiny kid, and by the final season, he’d shot up noticeably.
For context, the actor was born in 1998, so he was roughly 12–16 during the series (2010–2014). Height can vary a lot at that age, but fan forums and a few interviews from the time suggest he stabilized around that range. It’s wild to think how much taller he might be now, though! Makes me want to revisit the show just to spot the growth spurts.