How to shrink a swimsuit

Swimsuits stretch out over time, becoming baggy and ill-fitting. You can shrink your swimsuit to its original size with a few simple techniques—even if it has lost its shape or elasticity.

Here's how to restore your favorite bathing suit to its former glory.

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Why do swimsuits stretch out?

Boiling method

Hair dryer method

Iron method

Dryer method

Different types of fabrics and shrinking

Why do swimsuits stretch out?

Swimsuits stretch out for any or a combination of the following reasons:

Chlorine, a common pool chemical, weakens the fabric fibers, causing swimsuits to sag and stretch over time.
Saltwater breaks down the delicate fibers in swimwear. Your swimsuit loses its shape and elasticity because of this damage.
Sunlight also wreaks havoc on swimsuits. UV rays from the sun degrade the material, leading to a loss of shape and stretch.
Body soil, such as sweat, sunscreen, and oils from your skin, accumulates on the swimsuit fabric over time. This buildup breaks down the fibers and causes stretching.
Your body type and body shape also influence how quickly your swimsuit stretches out.
Harsh detergents, rough wringing, and dryer heat stretch the delicate fibers and elastic that help keep your swimsuit's shape intact.

Let’s see methods you can use to make your swimsuit great again.

The boiling water method

The boiling water method is an aggressive yet effective way to shrink your stretched-out bathing suit. Heat causes the fibers to contract and tighten. This method works well for swimsuits made from synthetic fibers, such as nylon or spandex.

Here’s how to tighten your swimsuit with boiling water:

Fill a large pot with clean water and bring it to a boil. You can also add a cup of table salt to the water, as salt shrinks the swimsuit fibers.
Once the pot of water reaches a rolling boil, remove it from the heat.
Carefully submerge your swimsuit in the hot water.
Let the swimsuit soak for 5–10 minutes (depending on how much you want to shrink it).
Use a pair of tongs or a wooden spoon to remove the swimsuit from the water. Be cautious, as the swimsuit will be hot.
Gently squeeze out the excess water; do not wring or twist, as this causes damage.
Lay the swimsuit flat on a clean towel. Gently roll the towel with the swimsuit inside to remove the remaining water.
Lay the bathing suit flat to air dry. Keep it away from sunlight or heat sources.

While the boiling water method is effective, use it sparingly. Repeated exposure to high temperatures weakens delicate swimsuit fabrics.

Hair dryer method

The hair dryer method is a more controlled and gentle way to shrink your bathing suit.

Here’s how to tighten your swimsuit with a hair dryer:

Wash your swimsuit in lukewarm water with a mild laundry detergent to remove any dirt, sunscreen stains, and chlorine residue.
Gently squeeze the excess water from the swimsuit. Do not wring or twist, as this causes damage.
Lay the swimsuit flat on a clean, dry towel. Gently roll the towel with the swimsuit inside to remove the remaining water.
Use a medium heat setting and hold the hair dryer about six inches from the swimsuit.
Slowly move the hair dryer over the swimsuit. Focus on the areas that need the most shrinkage. Do not hold the dryer in one spot for too long, as this damages the delicate fabric.
Periodically check the swimsuit's size and shape by gently stretching it. Stop the process once you've achieved the desired level of shrinkage.
Lay the swimsuit flat to cool and dry. Avoid direct sunlight or heat sources.

Iron method

The iron method uses direct heat to shrink the stretched-out swimsuit. The heat from the iron contracts the fibers and restores the swimsuit's original shape.

Here’s how to tighten your swimsuit with an iron:

Wash your swimsuit in cold water with a gentle detergent to remove dirt, sunscreen stains, and chlorine residue.
Gently squeeze the excess water from the swimsuit. Do not wring or twist the delicate fabric, as this causes damage.
Place the swimsuit on an ironing board and cover it with a clean, dry towel. This prevents direct contact between the iron and the swimsuit fabric.
Set your iron to the lowest heat setting.
Iron the swimsuit slowly and gently. Focus on the areas that require the most shrinkage, such as the bust, waist, or hips.
Periodically check the swimsuit's size and shape by gently stretching it. Stop the process once you achieve the desired level of shrinkage.
Hang the swimsuit to dry. Avoid direct sunlight or heat sources.

Dryer method

Dryer heat causes fibers to contract, restoring the swimsuit's original shape and size.

Here’s how to tighten your swimsuit with a dryer:

Wash your swimsuit in the washing machine using cold water and a mild detergent. This removes dirt, sunscreen, and chlorine residue that interferes with the shrinking process.
Once the wash cycle is complete, place the swimsuit in the dryer with a few clean, dry towels. The towels absorb moisture and prevent the swimsuit from getting damaged from heat exposure.
Set the dryer to the lowest heat setting. High temperatures damage the delicate material and cause the colors to fade.
Run the clothes dryer for a short cycle, typically 5–10 minutes.
Try on the swimsuit. If it hasn't shrunk enough, repeat the process for another short cycle.

How to shrink different fabric types

The type of fabric determines how much the swimsuit will shrink and which techniques will be most effective.

Polyester swimsuits

Polyester is durable, quick-drying, and resistant to chlorine and sunlight. Heat causes polyester fibers to contract, so polyester swimsuits shrink using the boiling water, hair dryer, or dryer method.

Nylon swimsuits

Nylon is elastic, durable, and resistant to abrasion. Nylon fibers, similar to polyester, contract when exposed to high temperatures because of their heat sensitivity. So, all heat-based methods effectively shrink nylon swimsuits.

Spandex swimsuits

Spandex, also known as elastane, is elastic and stretchy. It is commonly blended with other fibers (polyester or nylon) to create form-fitting, comfortable swimsuits. Because of its heat sensitivity, spandex responds well to shrinking methods that involve high temperatures.

Cotton swimsuits

Cotton is sometimes used in swimwear, particularly in casual or retro-style suits. While cotton is breathable and comfortable, it is less responsive to heat-based shrinking methods than synthetic fabrics.

Cotton swimsuits may shrink more when exposed to hot water and agitation, such as in a washing machine, but the results can be less predictable than when dealing with synthetic materials.

Choose high-quality SwimZip swimwear

SwimZip's swimwear features durable, quick-drying fabrics made from nylon and spandex, with a polyester lining for comfort and support. Our high-quality swimwear provides long-lasting UPF 50+ sun protection.

From men's swim trunks and women's swimwear to kids' sunsuits, sun hats, rash guards, and accessories, we’ve got you covered.

As one of the most trusted UPF 50+ brands, SwimZip is committed to keeping you and your loved ones safe from harmful UV rays.

Mom and daughter enjoy sun by the swimming pool in SwimZip Peachy Stripes one-piece swimsuits—How to shrink a swimsuit

Swimsuits FAQ

How can I shrink a bathing suit bottom?

You can shrink your bathing suit bottoms with the same methods used for shrinking the entire swimsuit. The common methods, such as boiling water, hair dryer, and ironing methods all effectively shrink swimsuit bottoms.

To shrink your bathing suit bottom, first identify the fabric type to determine the most suitable shrinking method. Synthetic fabrics such as polyester, nylon, and spandex respond well to heat, so using the boiling method or the dryer method on high heat will get the best results.

If your swimsuit bottom is made from natural fibers (for example cotton), use the hair dryer method or the iron method, as these fabrics are less heat-sensitive and more prone to shrinking when exposed to hot water and agitation.

Regardless of the fabric type, always start with the gentlest method to avoid over-shrinking or damaging your swimsuit bottom. If the initial attempt doesn't provide the desired level of shrinkage, try more intensive methods until you achieve the perfect fit.

Can you sew a swimsuit to make it smaller?

You can use a sewing machine to take in extra fabric and make a swimsuit smaller. This is a good option for swimsuits that are only slightly big. Use a stretch needle and polyester thread for the best results.

How do you fix a bathing suit that is too small?

If your bathing suit is too small, stretch it out by soaking it in cool water with a small amount of baby shampoo. Gently stretch the suit while it's wet and focus on tight areas, then rinse and lay flat to dry.

How do you get a swimsuit that fits perfectly?

To find the perfect swimsuit, measure your bust, waist, and hips, and check out our sizing chart. Look for suits with adjustable features such as ties or ruching. Try many styles, and choose one that makes you feel confident and comfortable.

How do you make yourself look skinnier in a swimsuit?

To look slimmer, choose dark-colored bathing suits with strategic cut-outs, ruching, or draping to create a flattering silhouette. Avoid ill-fitting suits that are tight or loose. High-waisted bottoms and one-piece bathing suits with vertical stripes also elongate your figure.