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Competitive Swimwear Sizing Guide

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Selecting the correct swimsuit size can be challenging, especially for athletes new to competitive swimming and fitness swimming. Sizing swimwear using only waist and chest measurements will get you headed in the right direction, but this is only the beginning.

Read on for Kiefer’s advice on how to get a great fit from your swimwear.

Swimwear Sizing Challenges

Generally speaking, swimsuit sizing charts provide excellent guidance. Nonetheless, two challenges remain, regardless of size chart accuracy:

  1. Swimmers may be unfamiliar with how to take measurements.
  2. Athletes may be unfamiliar with what a good fit  feels like.

How To Take Proper Swimsuit Measurements

Taking fresh measurements and matching them to a swimsuit size chart is the best approach for a great fit.

Here are some guidelines for making proper swimwear measurements:

  • Don’t take your own measurement – ask a friend to measure you.
  • Take measurements on bare skin!
    • Bonus Tip: If this isn’t possible, adjust measurements to remove measuring overstatements caused by bulk from clothing.
  • Use a soft tape to measure. No rulers – no metal tape measures – soft tape only!
    • Bonus Tip: The tape should lay flat, without indenting skin. Over-tightening distorts measurements.
    • Extra Bonus Tip: If a soft tape measure isn’t an option, use non-stretching string – and carefully match the string length to a reliable measurement tool.
  • Warning For Guys: Gentleman, your measurements are less challenging – but be careful! Remember:
    • Measure 1″ below your navel to determine your waist size. Waist measurement equate to the suit size, so a 32″ waist should order a size 32 suit.
    • Do not use the pants size shortcut! Pants size is not an accurate equivalent, because it is often chosen by the look or style of the fit, instead of an actual measurement. Save yourself some frustration and measure your waist.

Chest & Hips – Special Swimsuit Sizing Situations

All bodies are different, and women with greater variations between chest and hip size may want to consider downsizing or upsizing as follows:

  • Small Chest / Large Hips: Consider upsizing above chest measurement guidelines.
  • Big Chest / Small Hips: Consider downsizing below chest measurement guidelines.

What Not To Do:

  • Don’t reference a size from an old swimsuit!
    • Old suits can be stretched out and will not index your current sizing needs.
    • Department store swimsuits and fashion swimwear brands are not designed or cut to fit like fitness swimwear.
    • Sizes can vary across brands & suit cuts can change over time.
  • Don’t let someone else order for you! The fit of your swimwear is a personal preference – don’t let someone’s speculation about sizing get in the way of basic swimwear sizing strategies.
  • Warning For Guys – Don’t Use Your Pants Waist Size! Because pants size is often chosen to achieve a certain fit style, translating it your swimwear waist size isn’t recommended.

What Does A Great Swimsuit Fit Feel Like?

For best results and to maximize the life of your swimwear, Kiefer recommends that swimsuits provide a tight & supportive fit.

For swimmers that are skeptical about the benefits of tight-fitting swimwear, we offer the following encouragement:

  • The suit you are trying on is as tight as it’s ever going to be and will loosen over time.
  • The feel of the suit will change once you are in the water.
  • Bag = Drag! Any bag or wrinkles will cause unwanted drag during your race or workout.
  • Swimsuits are more than a means to cover your skin. Like running shoes, competitive swimwear is a piece of sports equipment. And like shoes that are too large, wearing an over-sized swimsuit will cause discomfort and hinder athletic performance.

Fit Differences Between Lycra vs Polyester Swimwear Material

  • Polyester material has a more tighter, more compressive fit and wears longer. This does not mean you should upsize for poly, but swimmers should consider sizing up if on the cusp on a larger size.
  • Lycra suits:
    • Have more stretch, but should still have a snug and supportive fit.
    • May need to be replaced semi-annually


It’s important to remember that Jammer cuts have changed over the last few years. Although Jammers used to fit lower on the waist, more current cuts have a higher waist. Here are some extra jammer fitting tips to help you determine what a great fit feels and looks like:

  • Jammers should be sufficiently snug at both waist and knee, to make getting 2 fingers under the fabric somewhat challenging.
  • Waist fit rules! Don’t worry about the leg cuff height, as this will vary for different body types.
  • Remember, your waist measurement equates to the suit size, so a 32″ waist should order a size 32 suit.

How Can I Tell If My Swimsuit Is Too Big Or Small?

Big – a swimsuit is too big if:

  • Suit material is wrinkled or bagging.
  • For women, swimwear is too big if:
    • Scooping at neck occurs when holding a “streamline” position.
    • Suit straps can be raised to ear height.
    • The open park of the suit back (below the intersection of the straps) lifts off the skin.

Small – a swimsuit is too small if:

  • It restricts or limits athletic range of motion.
  • Ouch – it hurts!
  • It limits your circulatory system – blood flow and/or breathing!
  • Putting it on is a struggle.
  • It causes excessive muffin topping anywhere on the body.
  • Your chest is spilling out of suit.

Whoa! Did you get all that?

I hope this helps you when considering sizing for your next swimsuit. Please share your comments – or any advice you have for swimwear fitting.

Do you have questions?

We’d be happy to help, just let us know!

See you at the pool,


About Robin Kiefer

Robin Spencer Kiefer is a lifetime fitness swimmer and endurance athlete. After becoming an Ironman in 2008, Robin continues to push the limits of marketing & parenting. He is the Vice President of Digital Marketing and Ecommerce at Kiefer.

Recent Comments (12)

Really helps…thank you…i would prefer to try on a suit, but no one around carries elite racing swimwear…St George, Ut…if im going to spend between $300 to $500… I want to try it on…i bought a kneehi made in japan and lucked out….At under $40… And it fit perfectly…

I’m glad it worked out – as you noticed, sizing somethings requires a leap of faith – but good measurements shorten the leap!
We’ll be following up with an article on “tech suit” sizing in the near future.
Thanks for your comments! See you at the pool…

You didn’t tell how to go from measurement in inches to swimming suit size!

Oops, quite right! Generally speaking, men’s waist measurements for men equate to the suit size, so a 32″ waist should order a size 32 suit. Women’s size conversions are much trickier – use the size chart assigned to each swimsuit for the best fit. thanks

Thanks for this Robin! I am short but with a very long torso. I’m trying my first poly suits as I am doing more water exercise. I finally found a size the gets on ok but I feel kind of “compressed” in the torso. Is this normal? Can I expect a poly suit to stretch over time? Is there a brand known to have longer torsos? Thanks!

Yes, it is very normal to feel compressed in Poly, and in the torso in particular. Polyester swimwear will stretch slightly and gradually over time. I haven’t seen Poly suits in a long torso, but Lycra Speedo Ultrabacks are available in long sizes.

I am trying to decide between a size 30 and a size 32 nike powerback tank swimsuit. I am a lap swimmer and want a polyester swimsuit. My shoulders seem to be a little red and my shoulders seem to ache a bit. It is a new suit so I don’t know if it will stretch. The 32 is more comfortable in the shoulders but seems to crinkle a little in the butt. I am a 35.5 bust, 29 waist, 36 hip, and torso is about 60.5

Checking with my coworkers; in the meantime, take it easy on those shoulders! thanks

Hi, i checked with Stacey Kiefer; she said that Nike suits traditionally run a little large. If you’re on the fence about sizing up or down, she recommends sizing down to the smaller size. Plus, the suit will stretch over time. hope that helps! let us know how it goes…

I just bought a Enduro Super, I haven’t used it yet. But I tried it on and it feels like my shoulders are being pulled down making me want to hunch over. Is that normal?

You bought an endurance fabric suit with a superproback? Endurance fabric will be very taught and compressive, but it should not limit your athletic motion. If the suit has the wrong fit it cold limit your performance- and give you a suit burn on your shoulders… please let me know what suit you bought specifically. thanks

The brand is the finals and it is an enduro stretch solids v-back.

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