Period Swim Short

Our most-requested swim style ever! Perfect for teens who want fuller coverage in the front and back—while being fully protected on their period. Wear it alone on light days, or with a tampon or menstrual cup on heavy days.

Layer 1: A silky-smooth top layer that sits comfortably against the skin.

Layer 2: A highly-absorbent middle layer designed with our leakproof technology to absorb about the same as 2-3 super tampons worth of period blood.

Layer 3: A waterproof outer layer prevents swelling.

Other Features:

- Bum coverage: Max

- Wide waistband for comfort

- Mesh interior lining

- Super discreet liner

- 50+ UPF protection

- Seawater and chlorine resistant

- Pair with matching Double Scoop Bikini Top

Finally! Max-coverage, period-proof swim shorts that have your back.
Image of a absorbancy surrounding text
Absorbs about the same as 2-3 super tampons worth of period blood.
Image of a moisture fabric surrounding text
Rapidly absorbs moisture to keep you fresh and dry.
Image of a light and comfy surrounding text
Thin, subtle, and designed to feel just like regular swimwear.
Image of a machine washable surrounding text
Simply machine wash cold and lay flat to dry.

Our most-requested swim style ever! Perfect for teens who want fuller coverage in the front and back—while being fully protected on their period. Wear it alone on light days, or with a tampon or menstrual cup on heavy days.

Layer 1: A silky-smooth top layer that sits comfortably against the skin.

Layer 2: A highly-absorbent middle layer designed with our leakproof technology to absorb about the same as 2-3 super tampons worth of period blood.

Layer 3: A waterproof outer layer prevents swelling.

Other Features:

- Bum coverage: Max

- Wide waistband for comfort

- Mesh interior lining

- Super discreet liner

- 50+ UPF protection

- Seawater and chlorine resistant

- Pair with matching Double Scoop Bikini Top

Machine wash cold and lay flat to dry. Do not bleach, iron, or dry clean.


Body: 85% Nylon, 15% Spandex

Lining: 85% Nylon, 15% Spandex

Gusset: Leakproof Technology®, Polyurethane Film


Additional Product Ingredient Information

For items with a 20% or more discount, you may exchange for another item or return for store credit. No refunds can be accommodated. 

Items marked as “Flash Sale” or “Clearance” are final sale, meaning no returns, exchanges or refunds can be accommodated. No exceptions. 

Please note: Sale items are not eligible for our First Pair Risk-Free Policy.

We offer free standard shipping on all orders over $70. We ship our items via DHL or Canada Post depending on your location. Please allow 1-2 business days for your items to be processed and shipped. During high volume periods, your order may take up to 7 business days to dispatch from our warehouse location.


US Orders: Please allow 3–10 business days for orders to arrive.

International Orders: Please allow 10–25 business days for orders to arrive.

NOTE: Orders placed on Friday after 1 PM will not be processed until the following Monday.

CANADIAN CUSTOMERS: Shop www.knixteen.ca to order in Canadian currency.

 FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
FOR THIS GENERATION
FOR THE PLANET
FOR REAL LIFE
nothing is TMI here—we promise.

Our period swim bottoms contain a triple-layer gusset that absorbs your flow and locks in leaks, whether you're in or out of the water. When they go in the wash with detergent, the blood releases through the top layer—leaving your swimwear fresh and clean for next time. Yes, your other clothes will remain stain-free!

Here's the breakdown of our 3-layer leakproof technology:

Layer 1: A silky-smooth top layer that sits comfortably against the skin.

Layer 2: A highly-absorbent middle layer designed with our leakproof technology to absorb up to 1-3 tampons worth of period blood.

Layer 3: A waterproof outer layer prevents swelling. 

Not always. When your flow is light, our swimwear can be worn alone without any additional period protection. On super heavy days, we recommend wearing a tampon or menstrual cup with your swimwear. Every period is different though, and we recommend doing whatever makes you feel most confident.

Machine wash cold and lay flat to dry. Do not bleach, iron, or dry clean.

Check out our size chart here. 

Yes! All of our regular price swim bottoms and one-pieces are eligible for a return or exchange within 30 days of delivery, as long as the original sanitary strip and tags are attached. Our swim tops are eligible for a return or exchange within 30 days of delivery with original tags attached.

Absolutely! The leakproof liner built into all of our period swimwear is undetectable, so they look and feel just like regular swimwear.

Our styles are made to fit teen bodies. For period swimwear in adult sizes, please visit Knix.

 COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
REUSABLE
COMFORTABLE
JUST PLAIN BETTER
Reviews
average rating 4.3 out of 5
Based on 241 reviews
  • 5 Stars
    155 Reviews
  • 4 Stars
    44 Reviews
  • 3 Stars
    17 Reviews
  • 2 Stars
    9 Reviews
  • 1 Star
    16 Reviews
84% of reviewers would recommend this product to a friend
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Review posted
Reviewed by Lauri H.
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Period Swim Short
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Period Swim Short
Rated 5 out of 5

Very happy

I liked the look of these online so decided to get the teen swim shorts even though I’m a 42 year old mom. I am very happy I did! I usually wear a size small in Knix clothing so I sized up to Medium in these. They are really flattering and super comfy! The gusset doesn’t feel uncomfortable or bunchy. Great product and incredibly fast shipping!

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Reviewed by Joslyn P.
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Period Swim Short
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Period Swim Short
Rated 5 out of 5

Super comfortable

My daughter feels so comfortable in these and true to size. She's happy that she can enjoy pool days!

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Reviewed by Sarah B.
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Period Swim Short
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Period Swim Short
Rated 5 out of 5

good quaility so far

The size lge fit my 11 1/2 year old daughter just right. She has worn them twice and they have done the job so far.

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Reviewed by Brittany E.
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Period Swim Short
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Period Swim Short
Rated 5 out of 5

Total lifesaver!

I bought these on a whim, not even knowing if my daughter would ever end up using them. Well, a couple weeks later, her period came the exact day we were going to go swimming so having them ended up working out perfectly. She had no leaks and could play comfortably all afternoon!

She’s 11, tall and slim and I usually buy her an XS in the underwear but since she’s right at the cusp of sizing up, I went for a Small so it should fit her next year too.

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Reviewed by Monique L.
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Period Swim Short
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Period Swim Short
Rated 5 out of 5

Perfect for summer camp

My daughter loved these at summer camp. Will be buying more for next summer!

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