The short version
- Wetsuit thickness is written torso/limbs in millimeters: a 4/3 has 4 mm on the core and 3 mm on the arms and legs.
- Rough guide: 3/2 for about 59–65°F, 4/3 for about 52–58°F, 5/4 for about 45–51°F, and hooded 5/4/3 or 6/5 below that.
- Add boots below about 52°F, gloves below about 50°F, and a hood below about 48°F.
- Adjust for wind, how long you're out, how much time you spend in the water, and whether you run cold.
- Below 70°F (21°C), paddlers should dress for falling in, not for the air.
Buy a wetsuit that's too thin and you'll be shivering out of the water after 40 minutes. Buy one that's too thick and you'll overheat, tire your shoulders, and leave it in the closet. Matching thickness to water temperature is the most important wetsuit decision you'll make. This is our complete chart, built from leading manufacturers' guidance, with the adjustments that make it fit how you actually use the water.
How to read wetsuit thickness
Wetsuit thickness is listed in millimeters, usually as two numbers. The first number is the torso, where your vital organs need the most warmth. The second is the arms and legs, which are kept thinner so you can move. A "3/2" is 3 mm in the core and 2 mm in the limbs. A three-number suit such as a 5/4/3 adds a thinner zone, usually under the arms or on the lower legs, for flexibility.
Neoprene keeps you warm two ways. Its tiny closed gas cells insulate. And a thin layer of water trapped against your skin warms up to body temperature. Thicker neoprene insulates more, but only if the suit fits. A loose suit lets cold water flush through and you lose the warm layer. See How a Wetsuit Should Fit.
The chart: wetsuit thickness by water temperature
| Water temp (°F) | Water temp (°C) | Suit | Accessories | Typical feel |
|---|---|---|---|---|
| 75°F and up | 24°C and up | Rash guard or UPF top. A 0.5–1 mm neoprene top for long sessions. | None | Tropical snorkeling, peak-summer swimming |
| 70–74°F | 21–23°C | 1–2 mm top, vest, or spring suit | None | Warm summer water that still chills you on long sessions |
| 66–69°F | 19–21°C | 2 mm spring suit, long john, or shorty | None | Refreshing; cool once the wind picks up |
| 59–65°F | 15–18°C | 3/2 full suit | Optional thin boots on windy days | Cool. The everyday all-rounder in many coastal areas. |
| 52–58°F | 11–14°C | 4/3 full suit | Boots recommended, gloves optional | Cold. Classic spring and fall water in temperate regions. |
| 45–51°F | 7–11°C | 5/4 full suit, hooded preferred | Boots and gloves, hood near the low end | Very cold. Hands and feet go numb fast without neoprene. |
| Below 45°F | Below 7°C | 5/4/3 or 6/5 hooded, 7 mm or a drysuit for long exposure | 5–7 mm boots, thick gloves or mitts, hood | Painful on immersion. For experienced, well-equipped people only. |
This chart blends temperature guides from established wetsuit makers. One widely used US guide puts the 3/2 at 59–65°F, the 4/3 at 52–58°F and the 5/4 at 45–51°F, and recommends boots below 52°F, gloves below 50°F and a hood below 48°F. A European guide from a major brand gives a 3/2 or 4/3 for 12–17°C (55–64°F) and a 4/3 or 5/4 for 8–11°C (48–54°F). The ranges overlap because people, activities and suits differ. If you fall between two rows, use the adjustments below.
For most people in one region, a two-suit quiver covers the year. In California or the Mid-Atlantic, that's usually a 3/2 for summer and a 4/3 with boots for the shoulder seasons. In New England or the Pacific Northwest, it's a 4/3 plus a hooded 5/4. See our wetsuit temperature guide for help choosing.
Adjustments: when to go thicker or thinner
| Factor | Go thicker if… | Go thinner if… |
|---|---|---|
| Wind and air temperature | Air is colder than the water, or it's windy (wind chill on a wet suit is brutal) | Hot, still, sunny days |
| Time in the water | Long sessions, or you sit still a lot (surf lineup, snorkeling, diving) | Short, high-output sessions |
| Activity level | Low exertion: floating, fishing, teaching kids | High exertion: hard paddling, open-water swimming |
| Your body | You run cold, are slim, or are a child | You run hot |
| Suit construction | Flatlock seams or an older, worn suit | Sealed seams and a thermal lining |
Seam construction changes how warm a given thickness feels. Flatlock stitching lets some water through and suits warm water and 2 mm suits. Glued and blind-stitched (GBS) seams cut water entry and are standard on most 3/2s. Sealed or taped seams block water almost completely and are standard on 4/3s and thicker.
Activity-specific advice
Surfing and bodyboarding
You're wet the whole time and sit still between waves. Use the chart as written. Chest-zip and zipless suits flush less than back-zip suits at the same thickness.
Paddleboarding and kayaking
Major wetsuit makers point out that paddlers spend most of their time out of the water, so many choose thinner suits. That's fine for warm water. But in water below 70°F, the National Center for Cold Water Safety recommends dressing for immersion, because a fall triggers cold shock no matter how dry you planned to stay. For SUP and kayak in cold water, choose your suit for the swim, then add a windproof layer on top if you're cold. For very cold water, a drysuit is the paddler's tool. Read Cold Water Shock and the 1-10-1 Rule.
Snorkeling and diving
You're horizontal, still and often in the water for an hour or more. Even 78–82°F water can chill you over a long session, so a 1–3 mm suit is common in the tropics. Divers usually go thicker than surfers at the same surface temperature, because water gets colder with depth and neoprene compresses and insulates less as you descend.
Tow sports
Short, intense rides with lots of time sitting in the boat. A 2 mm or 3/2 suit (or a neoprene top) under a life jacket extends the season. Make sure your life jacket still fits snugly over the suit.
A wetsuit adds some buoyancy, but it is not a life jacket and doesn't count as one. Wear an approved life jacket over your suit for paddling, boating and towing.
Accessories: the cheapest warmth you can buy
- Boots (2–7 mm): Cold feet ruin a session fast. Split-toe boots grip boards better. Round-toe boots are warmer.
- Gloves (2–5 mm) or mitts (5–7 mm): Hands lose function quickly in cold water. Mitts are warmest, and five-finger gloves give the most dexterity for paddling and rigging.
- Hood (2–3 mm): Takes the sting out of duck dives, cold spray and wind. It also limits the cold-water and wind exposure linked to "surfer's ear" (bony growths in the ear canal).
- Neoprene top or vest: Layer under a full suit to stretch a 3/2 a few degrees colder, or wear one alone on warm-water days.
Shop the gear: Wetsuits, boots, gloves & hoods · Surf gear
Common mistakes
- Dressing for the air. Warm spring days over cold water are when cold-shock accidents happen.
- Going too thick "just in case." You'll overheat and tire out. A suit that's too thick also restricts movement.
- Ignoring fit. A loose 5/4 can be colder than a snug 4/3.
- Skipping boots. Below about 52°F, cold feet will end your session before your core gets cold.
- Keeping a dead suit. Neoprene loses warmth as it ages and compresses. One US maker estimates a well-cared-for suit lasts about 2–4 years of regular surfing.
FAQ
What thickness wetsuit for 60-degree water?
A 3/2 full suit is the standard choice around 59–65°F. If it's windy, you run cold or you'll be in for a long session, step up to a 4/3 or add thin boots.
What wetsuit for 50-degree water?
At about 50°F, most people want a 5/4 (a 4/3 at the very least) with boots and gloves. Hooded models are worth it as you approach the high 40s.
Do I need a wetsuit to paddleboard?
In warm water, no. Below 70°F, plan to fall in at some point and dress for that. A 3/2 or 4/3, or a drysuit for very cold water, plus a life jacket, is the safe setup.
Is a 3/2 or 4/3 better as a first wetsuit?
Choose the suit for the water you'll use most. In mild coastal climates, the 3/2 is the most versatile. In colder regions or for shoulder-season use, a 4/3 covers more of the year.
How warm is a shorty?
A shorty (short arms and legs, usually 2 mm) is for about 66°F and up, or for active sessions on warm days. It leaves your limbs exposed, so it cools fast in wind.