By Kai Lani | WAHA Surf Shop
If you are shopping for a full wetsuit, you have probably noticed the numbers. 3/2. 4/3. Maybe even 5/4. These are not random. They tell you exactly how thick the neoprene is in different parts of the suit, and picking the right one makes a real difference in how long you can stay comfortable in the water.
Most surfers end up choosing between a 3/2 and a 4/3 because those two cover the widest range of conditions. So which one do you actually need? Let's break it down.
What the Numbers Mean
The first number is the thickness of neoprene around your torso, measured in millimeters. The second number is the thickness around your arms and legs. Your core needs the most insulation because that is where your vital organs are. Your limbs need more flexibility for paddling and popping up.
- 3/2mm: 3mm in the chest and back, 2mm in the arms and legs. Thinner overall, which means more stretch and easier paddling.
- 4/3mm: 4mm in the chest and back, 3mm in the arms and legs. An extra millimeter might not sound like much, but it makes a noticeable difference in warmth, and a slight difference in flexibility.
The tradeoff is simple. Thicker neoprene traps more water against your skin (which your body heats up), keeping you warmer. But thicker neoprene also means more resistance when you move. A 3/2 feels noticeably more limber than a 4/3, especially during long paddle-outs.
When to Wear a 3/2
A 3/2 is the go-to wetsuit for water temperatures between 58 and 68 degrees Fahrenheit (roughly 14 to 20 Celsius). That covers spring through fall in most temperate surf spots. Think Southern California from April to November, Portugal in summer, most of Australia outside winter months.
The main advantage of a 3/2 is freedom of movement. Less neoprene means less restriction on your shoulders and arms. If you surf often and the water is not truly cold, a 3/2 lets you paddle harder with less fatigue. For sessions under two hours in mild water, it is the better choice almost every time.
Some surfers run warm naturally and find a 3/2 works fine even in water down to 55 degrees. Others start feeling the chill at 62. Your personal cold tolerance matters here.
When to Wear a 4/3
A 4/3 is built for water temperatures between 48 and 58 degrees Fahrenheit (roughly 9 to 14 Celsius). Winter in Northern California, the UK and Ireland most of the year, New England from October through May, Oregon and Washington year-round for many surfers.
The extra millimeter of neoprene provides significantly more insulation. In water below 55 degrees, a 3/2 starts failing within 30 to 45 minutes for most people. A 4/3 extends your comfortable session time by another 30 minutes or more, depending on conditions.
Modern 4/3 wetsuits have gotten much more flexible than they were even five years ago. Premium suits from brands like O'Neill, Rip Curl, and Xcel use stretchy neoprene blends that feel surprisingly close to a 3/2. You will still notice a difference, but it is not the stiff rubber experience it used to be.
Temperature Comparison
| Feature | 3/2mm | 4/3mm |
|---|---|---|
| Water Temp Range | 58-68F (14-20C) | 48-58F (9-14C) |
| Torso Thickness | 3mm | 4mm |
| Arm/Leg Thickness | 2mm | 3mm |
| Flexibility | Excellent | Good (slightly stiffer) |
| Best Season | Spring, summer, fall | Fall, winter, early spring |
| Price Range | $150-400 | $180-450 |
Can One Wetsuit Cover Both?
If you only want to buy one wetsuit, pick the thickness that matches the conditions you surf in most often. If 80% of your sessions are in 60-degree water and you only surf winter occasionally, a 3/2 is your best bet. If you live somewhere with genuinely cold water most of the year, the 4/3 is the obvious call.
For year-round surfers in places with real seasonal swings, owning both is worth it. A good wetsuit lasts 2 to 4 years with proper care. Spending $300 to $400 total on two suits means you are always comfortable, no matter the season. You will surf longer sessions and enjoy them more. That is hard to put a price on.
One more thing to consider: wind chill. On a calm day a 3/2 might handle 56-degree water fine. But add a 15-knot offshore wind and you will be shivering between waves. If your local break is windy, lean toward the thicker suit for borderline temperatures.
For a broader look at what to wear in different conditions, check out our surfing clothing guide. If you are still early in your surfing journey and want to understand the full gear picture, our wetsuit overview covers everything from entry-level to high-end suits. And for warm water days when a full wetsuit feels like overkill, take a look at the wetsuit vs rash guard comparison.
The history and science of wetsuits is genuinely interesting if you want to understand why neoprene works the way it does.