A rash guard should fit like a second skin.

Tighter than you think. If it feels a little snug in the shop, that’s probably the right size — it’ll stretch slightly when wet and will stay put instead of flapping around.

The whole point of a rash guard is to prevent chafing from your wetsuit or board. Baggy fabric creates friction, which causes the exact rash you’re trying to avoid. It also traps water and creates drag. You want it snug but not so tight you can’t breathe or paddle.

For material, look for a nylon/spandex blend — 4-way stretch is ideal. Flatlock seams matter more than the logo. UV protection (UPF 50+) is nice if you’re going without a wetsuit. Thickness: 1mm is standard for warm water; 2mm adds a little warmth but less flexibility.

Don’t overthink the brand. A $40 no-name one that fits well beats a $100 branded one that’s loose.

Your rash guard should feel like you forgot you’re wearing it — that’s the fit you want.