How to Choose the Right Wetsuit | A Buying Guide

Posted by IST on Sep 23, 2019 11:02:38 AM

If you live outside of the tropics and you plan to spend any extended amount of time outdoors and underwater, you're going to need a wetsuit to help keep you warm, happy, and alive. We put together a wetsuit buying guide to help you learn what to look for, whether it’s your first one, or you’re already looking for your next one. A wetsuit is an investment, and the effort and time you put into choosing the right fit for you now, will reward you in the water with enjoyable and comfortable diving experiences for the foreseeable future. The key factors include:

  1. Getting a great fit
  2. Choosing the best cut and thickness
  3. Important construction details
  4. Head, hands, and feet


How Do Wetsuits Work?

Wetsuits are designed to keep a body warm for extended periods of time in cold water, and in the most extreme cases, help prevent hypothermia. A large volume of cold water can absorb heat from your body much quicker than air, so it's important to get the right equipment.

The neoprene wetsuit as we know it today was originally invented in 1952 by Hugh Bradner, a physicist, UC Berkeley professor, and life-long diving enthusiast. Wetsuits are typically made of neoprene, a soft, flexible, sponge-like, closed-cell, foam rubber material full of tiny densely packed air bubbles.

Neoprene is an insulator. It resists the transfer of heat, and acts as a barrier that prevents heat from escaping your body from contact with the large volume of water outside the suit (heat loss by conduction). Heat tends to go from warmer objects to colder objects, toward achieving an equilibrium, where both objects have the same resulting temperature. An ocean, lake, pond, or swimming pool can hold a lot more heat than your body can make over time. Without a wetsuit, your body would gradually approach the same temperature as the water (not good). The little trapped air bubbles in the neoprene are responsible for its high resistance to heat loss. Neoprene rubber conducts heat 10x slower than water, and still air conducts heat 20x slower than water (moving air is a whole other story though). 

The less water allowed in the suit, the better. Contrary to popular belief, having water in your wetsuit isn’t what makes it work. While a thin layer of water warmed by the body can help insulate you, the neoprene rubber and the tiny trapped air pockets do the bulk of the work. No suit will ever be completely air-tight or water-tight, so water will inevitably be present in a small enough quantity that your body can warm it.


Getting a Great Fit

The first thing you'll need to do is take your 3 key measurements: chest, waist, and hips. Pay attention to the manufacturer’s sizing chart. If you don’t know your measurements, you’ll need a tailor’s or sewing measuring tape to measure the circumference of your chest at its widest point, the circumference of your natural waist, and also of your hips. It’s easiest to do this standing in front of a mirror in your undies. For more detail on how to take your measurements, check out this guide.

measure the circumference of your: chest, waist, and hips
The essential measurements (from left to right): chest circumference, waist circumference, hip circumference.

Wetsuits are meant to fit tightly, but you should still be able to breathe easily, and you shouldn’t be losing circulation to your hands or feet. On the flipside, you want to make sure there’s not excess material or folds on your back or your limbs. A loose-fitting wetsuit will allow too much water to flow in and out, causing you to quickly lose heat (heat loss by convection). That makes it hard to stay comfortably warm on a dive of any duration. Lots of water moving in and out of your wetsuit is called flushing, and a little is called seepage. Both are bad for the quality of your dive and neither sound remotely sexy. They should be avoided and prevented, and that's accomplished first and best by getting the right fit.


Choosing Cut & Thickness

Wetsuits are available in a range of styles (or cuts), and thicknesses. Determining the right cut and thickness depends on 4 factors that affect temperature and mobility:

  • the conditions where you'll be active
  • your body’s tolerance for cold
  • the range of motion required for the activity
  • how active you'll be

Generally, colder seasons and conditions require more body coverage, and thicker material, while warmer seasons and conditions require less coverage, and thinner material. Your tolerance for cold will also be an important factor in choosing the right suit.

Neoprene can be quite stiff, especially when it’s thick and stuck to your skin. That can limit your ability to make big movements easily or comfortably. Surfing, kayaking, or triathlons require more flexibility and thinner material especially around the shoulders and joints for easier mobility. Activity also warms the body. A more active sport may also allow you to wear a lighter suit. If you can tolerate the cold better than the average person, you might also be able to wear a thinner suit to gain improved mobility in the water. Scuba diving, on the other hand, typically involves slower and smaller movements in deeper colder water. Thicker material and more coverage would make more sense in this case.


Typical cuts

Wetsuits are usually available as a single-piece or top in different arm and leg lengths. A full jumpsuit covers up the whole body up to the base of the neck and out over the wrists and ankles. This kind of cut is best for cold conditions. A springsuit or shorty covers a little less, reaching to just above the elbows and just above the knees. This is better for warmer conditions. You can also find neoprene jackets and separate tops, and less commonly in an overall style sleeveless cut that fully covers the legs down to the ankle.


Pictured Left to Right: Full Jumpsuit, Springsuit (Shorty), Neoprene Jacket


Neoprene thickness

Thicker neoprene typically provides better protection from the cold than thinner neoprene (putting more tiny air bubbles between you and the water. When you’re shopping for a wetsuit, you’ll often see a set of numbers that look like fractions. They’re indicators of the mm thickness of different parts of a wetsuit.

  • A single number means the whole suit is made out of the same thickness of neoprene.
  • Two numbers first show the thickness of the torso, and then a different thickness for the limbs. For instance, a 4/3 is made of 4mm thick neoprene to cover the torso, and 3mm neoprene to cover the limbs. This is usually done to provide more insulation for the core without sacrificing as much mobility, or vice versa.
  • Three numbers mean the arms are also made with another thickness of neoprene different from the legs or torso. So a 6/5/3 is made of 6mm thick neoprene to cover the torso, 5mm on the legs, and 3mm on the arms.

wetsuit thicknesses examples: 3mm, 4/3, 6/5/3

Some examples that break down wetsuit numbering

Here are some general recommendations that you can base your final decision on in terms of cut and thickness. Remember take into consideration your own cold tolerance, and your expected level of activity as well:

temperature chart and wetsuit and gear recommendations

A chart of basic recommendations. Wear thicker materials and increase cover in colder conditions.


Important Construction Details

Construction and design details in how your wetsuit is made can incrementally improve its effectiveness, and the quality and comfort of your dive, as well as the lifespan of your wetsuit. A lot of little improvements can add up to big gains. Here are a few things to look for:


Seam types

The 4 most common types of seams are:

  1. Overlock - the least expensive kind of stitching, and also the least flexible, with poor water-tight qualities. Overlock stitching creates a raised bump along the seam that can rub and feel uncomfortable to wear. You may see this on the most inexpensive wetsuits. Avoid this if you can.
  2. Flat-Lock - an inexpensive kind of stitching that's flexible and durable, but not water-tight. You'll see this mostly on thinner wetsuits. The stitching penetrates both sides of the material and makes lots of little holes that can lead to a bit of seepage. Most common on entry-level wetsuits.
  3. Glue and Blind-Stitched - found on higher end wetsuits, the neoprene is butted together and the seam is glued first and then stitched together from only one side of the wetsuit. Since the stitching doesn't penetrate both sides of the neoprene, this stitch is very water-tight, and also more flexible. On thicker wetsuits, you may see blind stitching on both the inside and outside.
  4. Welded Seams - can be done with or without stitching the neoprene first. Flexible and water-tight. Goes by many names. It's durable, flexible, and usually found only on high-end wetsuits.

Additionally, you may find some seams are taped for added durability and protection against seepage, in just a few key areas, or up to a fully taped wetsuit, usually on the inside, but sometimes found on the outside of a wetsuit.



You'll find 3 main kinds of zippers on wetsuits:

  1. Back zipper - the most commonly available kind, and the easiest to put on.
  2. Front zipper - does a better job reducing flushing at the neckline, but harder to put on.
  3. Zipperless - the least common and only available on wetsuits made with very stretchy types of neoprene material. 


Insulating Extremities: Head, Hands, and Feet

In more severe temperatures, you’ll most likely need to shield more parts of the body from cold than a wetsuit can cover alone. Neoprene hoods, booties, and gloves help to cover and keep warm all the areas left exposed by a typical full suit. Without them, cold hands, face, and feet can become extremely uncomfortable or painful. That could ruin an otherwise positive diving experience. 



A lot goes into deciding which wetsuit to buy, but at least now, you’re better equipped and more knowledgeable to buy your first (or next) wetsuit. Remember to have your measurements on-hand and consider the type of activity and the temperature range you'll be diving in most often. If you’re looking for a good dependable wetsuit for diving, why not check out IST’s acclaimed WS-80, rated a Best Buy by Scuba Diving Magazine’s Scuba Lab.

If buying your own wetsuit still seems too complicated or expensive, or you just aren't ready to take the plunge yet, don't let that stop you from diving. You can rent first, visit your local diving shop to try one on in-person, or there’s always this:



Topics: Product Guides, Beginner, Wetsuits