Thickness follows the water, not the air. Find your sea temperature, read across, and buy the suit that fits snug with no gaps at the neck, wrists and lower back.
| Water | Suit | Extras |
|---|---|---|
| 72 °F / 22 °C and up | Rash guard or 1 mm top | |
| 65–72 °F · 18–22 °C | 2 mm springsuit | |
| 60–65 °F · 15–18 °C | 3/2 mm fullsuit | |
| 54–60 °F · 12–15 °C | 4/3 mm fullsuit | 3 mm booties |
| 47–54 °F · 8–12 °C | 5/4 mm hooded | 5 mm booties, 3 mm gloves |
| below 47 °F · 8 °C | 6/5 mm hooded | 7 mm booties, mitts |
A suit works by trapping a thin layer of water and warming it. Gaps flush that layer out every duck dive, so a snug 3/2 outperforms a loose 4/3. Try it on: it should be hard to get into, with no folds at the lower back and no gap at the neck, and you should still be able to raise your arms over your head.
Chest zip and zipperless suits flush less than back zips and are warmer for the same thickness; back zips are easier to get into and cheaper. For cold water pick chest zip.
The calculator suggests a thickness from your water temperature and links to suits at that thickness; the full guide has the reasoning.
Browse wetsuits by thickness →
More guides: Beginner board size · Soft-top or hard board · How many liters is too many · Foamie to fiberglass.