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

• Measure around your neck at the point where the collar naturally sits, then add half an inch for breathing and swallowing room.
• The two-finger test: with the top button done, you should be able to slide two fingers comfortably between your neck and the collar.
• A collar that's too tight is one of the most common causes of neck irritation and redness by the end of a workday.
• Collars stretch slightly after repeated washing — buy true to size rather than compensating for future stretch, which often never fully happens.

The fit-and-fabric-health takeaway: The collar sits against the most sensitive skin on the body (the neck) for hours at a time — this is the single fit point most linked to visible skin irritation.

Next up: check out our guide on why fabric choice matters for skin health.