Wetsuit Thickness Explained: How Many mm Do You Need?

You've decided to take the plunge and get a wetsuit. You start browsing online, and you're immediately confronted with a confusing array of numbers: 2mm, 3/2, 4/3, 5/4/3... What does this code mean? Is a 4/3mm suit really that much warmer than a 3/2mm? If you choose the wrong one, will you be shivering in the water or overheating and unable to move freely?

Choosing the right wetsuit thickness is the single most important decision you'll make to ensure you are comfortable and safe in the water. But it doesn't have to be complicated. This is your simple, clear guide to understanding wetsuit millimeters. We'll break down what the numbers mean, provide a handy temperature chart, and explain the crucial trade-off between warmth and flexibility. As the material experts at https://neoprenecustom.com who create the very neoprene that keeps you warm, we want to empower you to make a confident choice.

The #1 Rule: Thickness = Warmth

The science is simple: a wetsuit works by trapping a thin layer of water between your skin and the suit. Your body heats up this water, and the neoprene foam insulates it from the cold water outside.

Neoprene is a foam filled with thousands of tiny, sealed bubbles of gas. This trapped gas is a fantastic insulator. Therefore, the core principle is:

A thicker sheet of neoprene has more insulating gas bubbles and will keep you warmer.

Decoding the "Slash": What a 3/2 or 4/3 Really Means

You'll rarely see a wetsuit that is just one single thickness. High-performance wetsuits use a clever strategy called "combination thicknesses" to give you the best of both worlds.

• The First Number (e.g., the '3' in 3/2): This is the thickness of the neoprene in the most critical areas for warmth: your torso and upper legs. This keeps your core body temperature stable.

• The Second Number (e.g., the '2' in 3/2): This is the thickness of the neoprene in areas that require maximum flexibility: your arms, shoulders, and lower legs.

So, a 3/2mm wetsuit has 3mm of neoprene on the chest and back, and 2mm on the arms and legs. A 5/4/3mm suit is even more specialized, with 5mm on the torso, 4mm on the legs, and 3mm on the arms. This strategic placement gives you warmth where you need it most and flexibility for paddling and movement.

The Ultimate Wetsuit Thickness & Temperature Chart

This chart is your go-to guide. Find the water temperature you'll be in, and it will tell you the recommended wetsuit thickness.

Important Considerations:

• Wind: Strong wind can make the air feel much colder. If it's windy, consider going one step thicker.

• Activity Level: A highly active surfer generates more body heat than a scuba diver who is moving less.

• Personal Cold Tolerance: Everyone is different! If you know you get cold easily, always err on the side of a thicker suit.

The Trade-Off: Warmth vs. Flexibility

Why not just buy a 7mm suit for everything? Because thickness comes at the cost of flexibility.

• A thin 3/2mm suit feels incredibly light and flexible. It allows for easy paddling and a full range of motion.

• A thick 5/4mm suit is noticeably heavier and stiffer. It will keep you very warm, but paddling will require more effort and can be more fatiguing.

Choosing a wetsuit is about finding the perfect balance for your specific conditions and activity.

You've chosen the perfect thickness. But is a 4/3mm suit from a budget brand the same as a 4/3mm from a premium brand? Absolutely not.

The temperature ratings on our chart are based on a high-quality neoprene foam (like a high-CR blend or 100% CR).

• High-Quality Neoprene: Has a dense, uniform closed-cell structure that provides maximum insulation.

• Low-Quality Neoprene (like a cheap SBR foam): Has a less effective cell structure, absorbs more water, and compresses easily. A cheap 4/3mm suit might only provide the warmth of a high-quality 3/2mm suit.

This is the hidden factor in wetsuit performance. As a manufacturer of these materials at https://neoprenecustom.com, we know that the chemical composition and the manufacturing process are what create a truly warm and durable foam.

When you invest in a wetsuit from a reputable brand, you're not just paying for the logo; you're paying for the superior performance of the high-quality neoprene inside.

For brands looking to build a better-performing wetsuit, it all starts at the source. To learn about our different grades of high-performance neoprene, contact our material specialist, Kevin, at kevin@neoprenecustom.com.