Do Swimsuits Shrink or Stretch?

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I usually wondered why my swimsuit, which hugged my curves so perfectly, felt strangely loose after several swimming sessions. The next time I would wear the swimsuit, it was again fitting. Sounds familiar? Join me as I dive into my findings on how salt and chlorine in the pool water and the heat of the drier can make swimsuits shrink or stretch. 

Do Swimsuits Shrink or Stretch?

Swimsuits can shrink or stretch depending on the circumstances. For instance, swimsuits shrink when washed in hot water, dried in a drier, or when ironed due to the contraction of the fabric. On the other hand, they stretch when used in chlorinated swimming pool water or salty sea water due to the degradation of the spandex in the fabric. 

a woman lying on the beach wearing swimsuit

Will Swimsuits Shrink in Water?

Swimsuits, especially those made of fabric blends that include stretchy materials like spandex, are generally designed to hold their shape and fit even when wet. However, even these materials can shrink if exposed to very hot water, and it’s therefore advisable to wash them in cold water by hand.

When air drying, you should avoid direct sunlight as it can degrade the materials and make them lose elasticity and fit. Also, the exposure of a swimsuit to chlorine in swimming pools or salt in seawater can degrade the elastic fibers, causing it to lose its shape. This might give the appearance of shrinking.

However, a good quality swimsuit should return to its original shape once it dries due to the elastic nature of the materials commonly used. If your swimsuit continues to stay stretched out after drying, it may be a sign of wear and tear, and you might need to consider replacing it.

Why Do Swimsuits Lose Elasticity?

A swimsuit loses its elasticity because the elastic fibers break down and become weak. The elastic fibers in any article of clothing will eventually stretch out and become loose-fitting.

However, the elasticity in a swimsuit is more susceptible to stretching out quicker because of a few aspects such as:

  • Chlorine
  • Washing machines
  • Bleach and laundry detergent
  • Dryers
  • Hang drying
  • Wringing or twisting
  • Sunlight


Chlorine is a chemical in pools and hot tubs that keeps the water clean. What you might not know, is that it can ruin your swimsuit over time. Chlorine breaks down the elastic fibers and can fade the color in swimsuits. If you’ve ever had a white bathing suit turn yellow, chlorine is the reason why. 

Even though polyester fabric is chlorine-resistant, it won’t prevent the chlorine from breaking down the elastane in your swimsuit. The best way to avoid this is to either avoid chlorine or switch up swimsuits so they can last longer. 

a sexy woman wearing swimsuit sitting beside a boat

Washing Methods

You should almost never use a regular cycle to clean your swimsuit. A swimsuit is often small and full of thin strings which are delicate. If you want to wash your swimsuit in the washing machine, use cold water and use a delicate cycle. 

You can also purchase a mesh laundry bag to place your swimsuit in while in the washer. The most important thing to do is to rinse your swimsuit in cold water right after you’ve taken it off.  

This will get rid of some of the chlorine that’s been soaked into your suit. Avoid hard scrubbing or use of a bleach or laundry detergent when hand washing your swimsuit. Instead, use a mild hand soap that will be gentle on the fabric.

Drying Methods

If you use a dryer to dry the swimsuit after washing, the heat of the dryer will cause the elastic fibers of the swimsuit to break down, causing it to lose its strength. Air drying your swimsuit is a much better option as it won’t stretch out your suit. 

However, do not hang your swimsuit while it’s wet as it will pull down on the elastane in the swimsuit and weaken it over time. Squeeze the water out without wringing or twisting. Instead, place it on a towel and leave it to dry.

If it’s still dripping, roll the towel with the swimsuit, squeeze it and then unroll and leave it to dry. If possible, let the swimsuit dry indoors in a warm environment, rather than in the sun. The UV rays from the sun tend to break down the fabric in the swimsuit, making it fade.  

Should I Buy a Swimsuit in a Size Smaller or Should I Size Up?

I wouldn’t recommend sizing up or down when buying a swimsuit. Buy one that fits. Sizing down can make the swimsuit wear out sooner as it will have to excessively stretch to fit your body each time you put it on. Also, a smaller suit can give you an unflattering fit. 

Sizing up isn’t a good idea either. As the spandex in the swimsuit degrades over time, it might start losing elasticity, making the swimsuit appear more oversized. 

Woman adjusting her bikini bottom as she emerges from the pool

It’s, therefore, advisable to stick with your correct size when buying your swimwear. A smaller suit can create bulges and a larger swimsuit can leave you with a saggy bottom and not enough support in the chest.

How Do I Keep My Swimsuit So It Doesn’t Stretch?

Although it’s expected for the swimsuit to wear out over time, the following care instructions can help you extend the life of your swimsuit and ensure it maintains its fit and appearance.

  • Gently squeeze out excess water and lay it flat to dry after washing.
  • Avoid sitting directly on rough surfaces, which can cause the material to pill or snag.
  • Manufacturers know the exact blend of materials used in the swimsuit and provide instructions optimized for that blend. Follow the manufacturer’s instructions on the label 

Reasons Why Swimsuits Stretch

ReasonsWhat causes the stretch
Reason 1Chlorine in pools and hot tubs
Reason 2Washing using machines, bleach and detergents
Reason 3Drying using dryers or hang drying
Reason 4Wringing and twisting
Reason 5Drying in direct sunlight

Frequently Asked Questions

How Can I Shrink a Swimsuit?

You can shrink a swimsuit by putting it in hot water and putting it in the hot cycle of the dryer. Alternatively, you can iron your swimsuit using low heat settings when it’s still moist after washing.

Keeping in mind that most swimsuits are made of polyester fabric which is primarily made with polymer, heat makes them shrink.

Can an Overstretched Swimsuit Come Off When Swimming?

There are minimal chances of the swimsuit completely coming off when swimming, even if it’s over stretched and loose.

However, keeping in mind that some swimsuits, such as thong bikinis, have minimal coverage that only covers the genitals, overstretching can make the fabric loose when swimming, revealing your private parts.

Why Is My Swimsuit Disintegrating?

The main reason why swimsuits disintegrate is due to chlorine added to the swimming water. Generally, chlorine is a strong chemical that can make the fabric of the swimsuit fade, lose elasticity, and ultimately disintegrate.

That means there are higher chances of the swimsuit falling apart if you swim in public pools and spas.

100 Years of Bikinis | Glamour


Swimsuits are often made with durability in mind to withstand harsh conditions without stretching out. However, this depends on how you care for your swimsuit and how much you wear it. The above care tips will help you keep the swimsuit in its right sizing without stretching or shrinking.