Wetsuit Thickness Calculator: Which Wetsuit for Which Water Temperature?

Wetsuit thickness chart

Water temperature	Recommended protection
29 °C+ (84 °F+)	Rash guard, dive skin or 1–3 mm shorty
26–29 °C (79–84 °F)	3 mm full wetsuit
22–26 °C (72–79 °F)	5 mm full wetsuit, or 3 mm + hooded vest
18–22 °C (64–72 °F)	7 mm full wetsuit, hood, boots
12–18 °C (54–64 °F)	7 mm semi-dry with hood and gloves, or drysuit
Below 12 °C (54 °F)	Drysuit with undergarments

How the calculator works

The calculator starts with the water temperature and adjusts it into a "feels like" temperature based on two factors that make a big difference in practice:

• Your cold sensitivity. Body size, body fat, gender, age and fitness all affect how quickly you lose heat. People who feel the cold easily should move up a thickness.
• Number of dives. You don't fully warm up between dives, so heat loss accumulates over a day. On liveaboards with 3–5 dives a day, most divers wear more than they would for a single dive.

The result gives a starting point. Many other factors matter too: dive duration, depth (neoprene compresses and insulates less at depth), thermoclines, wind chill on the boat between dives, and how active you are underwater.

Tips for staying warm

• Fit matters more than thickness. A loose 7 mm suit can be colder than a snug 5 mm.
• Add a hood or beanie. Your head loses a lot of heat.
• Layer: a hooded vest or neoprene top under or over your suit adds a lot of warmth to your core.
• Stay warm between dives: dry off, put on a windproof jacket and get out of the wind.
• Eat and drink: your body needs fuel to produce heat. Warm drinks help.
• Don't pee in your suit to warm up. It feels warm briefly, then flushes out and cools you. (We all know people do it, though.)

Signs you're too cold

Shivering, clumsy hands, poor concentration and faster air consumption are all warning signs. Being cold also stresses your body, and some evidence suggests being cold at the end of a dive may affect decompression. If you start shivering underwater, signal your buddy and end the dive. Read more in our wetsuits and drysuits guide.

Water temperatures at popular destinations

• Red Sea (Egypt): 21–29 °C
• Thailand: 27–30 °C
• Maldives: 27–30 °C
• Mediterranean: 14–27 °C
• Mexican cenotes: 24–25 °C
• Galápagos: 16–28 °C

See all months in our dive destination calendar.

Wetsuit, semi-dry or drysuit?

Once water drops below about 18 °C, you're choosing between a thick semi-dry suit and a drysuit:

• Semi-dry (6–7 mm): cheaper and familiar to use; fine for 12–20 °C dives of moderate length.
• Drysuit: warmer, more comfortable between dives, and adaptable to any temperature by changing undergarments, but needs a specialty course and costs more.

If you'll dive in cold water regularly, a drysuit is usually worth it. For occasional cold trips, rent a semi-dry. Details in our exposure suit guide.

Don't forget weighting

Thicker neoprene floats more, so moving from a 3 mm to a 7 mm suit can mean adding several kilograms of lead. Always do a weight check when you change suits.

Frequently asked questions

What wetsuit do I need for 24 °C water?

A 5 mm full wetsuit is the usual choice for 24 °C water. People who run warm may be fine in 3 mm for a single short dive.

Is a 3 mm wetsuit enough for the tropics?

For water around 27–29 °C, a 3 mm full suit is enough for most divers. On liveaboards or if you feel the cold, consider 5 mm or add a hooded vest.