Let's get straight to it — here's what actually matters on this one.

• Gaping happens when the chest or shoulder measurement is too small for your build, pulling the buttonholes open under tension.
• It's most common on shirts sized to fit the waist, leaving the chest under-sized — a frequent issue for broader or more muscular builds.
• A quick fix is sizing up and having the waist tailored in, rather than sizing down and living with a gaping chest.
• Persistent gaping also means constant fabric strain at the button, which wears out that seam and thread faster than the rest of the shirt.

The fit-and-fabric-health takeaway: A gaping shirt exposes skin to more sun, friction from undershirts, and inconsistent airflow — a fit issue with a real comfort cost.

Next up: check out our guide on why trousers bunch up at the ankle.