What Wetsuit Thickness Do I Need? – Video Guide
Not sure whether you need a 3/2mm, 4/3mm or 5/4mm wetsuit? In this video, Jeff from Wetsuit Centre explains how wetsuit thickness affects warmth and flexibility, helping you understand which type of suit to consider for different seasons and water conditions. Watch the demonstration, then explore our detailed wetsuit thickness guide for further advice.
Video Transcript
Introduction – Choosing the Right Wetsuit Thickness
Hi there, Jeff here from Wetsuit Centre.
Today we're going to look at wetsuit thickness and how to decide which thickness is right for you.
When helping customers choose a wetsuit, there are a few key questions we ask to understand what they'll be using it for and the conditions they'll be going into.
Before we look at those questions, it's worth understanding what wetsuit thickness actually means.
What Do Wetsuit Thickness Numbers Mean?
If you look at a wetsuit, you'll often see thicknesses described as 3/2mm, 4/3mm, 5/3mm or 6/4mm.
These numbers refer to the thickness of the neoprene in different areas of the wetsuit, measured in millimetres.
For example, this children's wetsuit is a 3/2mm.
That means it uses 3mm neoprene around the main body and areas where insulation is most important, with thinner 2mm neoprene around areas such as the shoulders and arms.
The thinner material allows more flexibility and freedom of movement, while the thicker panels help retain warmth around the core.
You'll sometimes see three numbers, such as 5/4/3mm.
This generally means the wetsuit uses three different neoprene thicknesses in different areas of the body.
The precise panel layout varies between manufacturers and models, but the overall principle is the same: thicker materials provide insulation, while thinner sections allow more movement.
How Are Swimming Wetsuits Different?
Swimming and triathlon wetsuits use neoprene thickness differently from conventional surfing wetsuits.
In a swimming wetsuit, warmth is only one consideration.
Buoyancy and body position in the water are also extremely important.
Manufacturers may use thicker neoprene around the hips and legs to provide additional lift.
This helps support the swimmer's body position and can improve efficiency through the water.
At the same time, thinner and more flexible panels are often used around the shoulders to allow unrestricted swimming movements.
Swimming wetsuits commonly use panels up to around 4mm or 5mm thick, although the precise construction varies between models.
So, when choosing a swimming wetsuit, you need to consider buoyancy, flexibility and fit as well as warmth.
What Should You Consider When Choosing Wetsuit Thickness?
There are three main questions we ask customers.
First, where and when will you be using the wetsuit?
Water temperatures vary considerably depending on the season and your location.
Second, how well do you tolerate the cold?
Some people naturally feel colder than others, even when they're in the same water temperature.
Third, what activity will you be doing?
Surfing, paddleboarding, swimming and other watersports place different demands on a wetsuit.
Some activities require lots of movement, while others involve spending more time relatively still in the water.
Understanding these factors helps narrow down the most suitable wetsuit thickness.
3/2mm Wetsuits – Summer and Warmer Water
Let's start with the 3/2mm wetsuit.
This is what we'd typically describe as a summer wetsuit in the UK.
During the warmer months, particularly June, July, August and often September, water temperatures around the south coast can reach approximately 16–19°C.
Further north, particularly around Scotland, temperatures may be considerably cooler.
As a general starting point, a 3/2mm wetsuit is often suitable for water temperatures of approximately 14–19°C, depending on how well you tolerate the cold and how long you'll be in the water.
One of the biggest advantages of a 3/2mm wetsuit is flexibility.
Because the neoprene is relatively thin, it allows greater freedom of movement and doesn't feel as restrictive as a thicker winter suit.
In warmer water, you may not need the same level of thermal lining and insulation found in more expensive cold-water wetsuits.
That makes flexibility and comfort particularly important.
However, if you're someone who feels the cold easily, you might prefer a 4/3mm wetsuit even during some of the summer months.
For example, in water temperatures around 15–16°C, a 4/3mm suit could provide a more comfortable level of insulation for someone who tends to get cold.
The best choice depends on your own preferences and the conditions.
Shorty Wetsuits – Warm Summer Conditions
If you're someone who doesn't feel the cold particularly easily, you might prefer a shorty wetsuit in the warmest months.
A shorty usually has short arms and short legs, providing more freedom of movement and less insulation than a full-length wetsuit.
Many shorties use approximately 2mm neoprene throughout.
Some manufacturers also offer 3/2mm versions, while lighter 1mm options are available for particularly warm conditions.
When summer water temperatures reach around 19–20°C, a shorty can be a comfortable choice for many people, especially when the air temperature is warm.
In tropical conditions, you may only need a very thin wetsuit or no wetsuit at all, depending on the activity.
The key is to consider the water temperature, your tolerance for cold and how much flexibility you want.
4/3mm Wetsuits – Spring and Autumn
Moving up in thickness, we have the 4/3mm wetsuit.
This is one of the most versatile thicknesses for UK watersports.
It's particularly popular during spring and autumn, when water temperatures are cooler but you may not need the insulation of a full winter wetsuit.
As a general guide, a 4/3mm wetsuit is commonly used in water temperatures of approximately 10–14°C.
However, this can vary depending on the quality of the wetsuit and your individual cold tolerance.
Some surfers who are particularly comfortable in cold water continue using a 4/3mm during colder winter sessions.
Others prefer to move into a thicker wetsuit much earlier in the season.
Around the UK, the 4/3mm can be useful during October and November, sometimes extending into early December.
It's also commonly used during spring, when the sea is still cold despite warmer air temperatures.
That might mean April, May and even early June, depending on the location.
Why a 4/3mm Is a Good All-Round Wetsuit
A 4/3mm wetsuit can be an excellent choice if you only want to own one wetsuit and don't plan to use it during the coldest winter months.
For example, you might start surfing or paddleboarding in spring and continue through summer and autumn.
A good 4/3mm can cover a wide range of conditions.
It's warmer than a 3/2mm but generally more flexible and less bulky than a thicker winter wetsuit.
If you tend to feel the cold, it can also be a useful option during the warmer months.
For many UK watersports enthusiasts, a 4/3mm provides a very good balance between versatility, warmth and flexibility.
5/4mm and 6/4mm Wetsuits – Winter and Cold Water
Next, we move into winter wetsuits.
For UK winter conditions, you'll generally be looking at wetsuit thicknesses such as 5/4mm and 6/4mm.
Some manufacturers also produce even thicker wetsuits for particularly cold conditions.
A 5/4mm is a common choice for winter surfing, available in both hooded and non-hooded designs.
Thicker 6/4mm models are often supplied with an integrated hood to improve insulation around the head and neck.
As a general starting point, winter wetsuits become particularly important when water temperatures fall to around 9°C or below.
Here in Bournemouth, on the south coast, winter water temperatures can fall to approximately 7–9°C.
Further north, or in regions such as Scandinavia, water temperatures can be considerably colder, sometimes approaching 4–5°C.
In those conditions, additional insulation becomes increasingly important.
For many surfers on the south coast, a good-quality 5/4mm wetsuit provides suitable winter insulation.
However, if you feel the cold easily or regularly surf in particularly cold water, a hooded 5/4mm or thicker 6/4mm wetsuit may be more appropriate.
A hood can make a significant difference by reducing heat loss around the head and neck.
Choosing Between Warmth and Flexibility in a Winter Wetsuit
Wetsuit thickness is important, but it isn't the only factor affecting warmth.
Even within the 5/4mm category, different wetsuits can perform quite differently.
Some are designed primarily for flexibility, while others focus on maximum thermal insulation.
For example, an O'Neill Hyperfreak is designed to provide excellent freedom of movement.
It uses lightweight, flexible materials and a construction intended to minimise restriction.
That can make it particularly appealing if you spend a lot of time paddling or need plenty of shoulder movement.
At the other end of the spectrum, a wetsuit such as the Xcel Drylock places much greater emphasis on thermal insulation.
It features substantial thermal lining designed to retain warmth in cold conditions.
Other examples of warmth-focused wetsuits include the O'Neill Psycho Tech and Rip Curl Flashbomb.
These use more advanced thermal materials and insulation throughout the suit.
The trade-off is that additional lining can make a wetsuit slightly heavier or more restrictive.
So, once you've decided on the correct thickness, think about how you're going to use the wetsuit.
If you're constantly paddling and moving, flexibility may be your biggest priority.
If you spend a lot of time sitting in the water waiting for waves, or you tend to feel the cold, a warmer wetsuit with additional thermal lining could be the better choice.
Should You Choose a Thicker Wetsuit If You Feel the Cold?
One of the most important considerations is your personal tolerance for cold.
Two people can be in the same water temperature and have very different experiences.
Some people remain comfortable in a relatively thin wetsuit, while others need more insulation.
If you know you tend to feel the cold, choosing a slightly thicker wetsuit or one with more advanced thermal lining may improve your comfort.
For example, a 5/4mm wetsuit might be useful for someone surfing during colder autumn conditions, even when another surfer would be comfortable in a 4/3mm.
However, it's important to remember that thicker neoprene can reduce flexibility.
The aim is to find the right balance between insulation and freedom of movement.
Final Advice – What Wetsuit Thickness Do You Need?
Hopefully, this guide has helped explain how wetsuit thickness works and how to choose the right option.
As a general starting point for UK watersports:
- 3/2mm: Summer and warmer water, approximately 14–19°C.
- 4/3mm: Spring and autumn, approximately 10–14°C.
- 5/4mm: Winter and colder water, typically around 9°C and below.
- 6/4mm hooded: Very cold conditions or situations where additional insulation is particularly important.
These temperatures are general guidelines rather than strict rules.
The correct wetsuit thickness depends on your location, the season, your tolerance for cold and the activity you're doing.
Also consider the construction of the wetsuit, including its seams, neoprene quality and thermal lining.
Once you've considered those factors, you'll have a much clearer idea of which thickness is right for you.
Further Wetsuit Thickness & Buying Advice
Want to compare wetsuit thicknesses in more detail? Our comprehensive Wetsuit Thickness Guide includes recommended thicknesses for different UK water temperatures, seasons and conditions.
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