Most people assume ossification is done by the time you hit your late teens. Wrong! The long bones in your arms and legs—the ones that make you taller—stop growing in length around ages 16 to 18 for girls, and 18 to 21 for guys. That’s when the growth plates (the “soft spots” at the ends of bones) close up shop. But that’s just the beginning of the story.
Your flat bones, like your skull and your shoulder blades, ossify at a much slower pace. And the absolute final piece of the puzzle? The collarbone. Believe it or not, your clavicle doesn’t finish fusing into one solid piece until you’re between 25 and 31 years old. Yeah, you read that right—your skeleton isn’t fully adult until your late twenties or early thirties. Pretty crazy, huh?
