Period Swim Board Shorts

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, with a tampon or menstrual cup on heavy days or whatever works for your flow.

Other Features:
- Bum coverage: Max
- Wide waistband for comfort
- Mesh interior lining
- Super discreet liner

Pair with matching Double Scoop Bikini Top

The #1 essential for swimming freely and fearlessly on your period.
Image of a absorbancy surrounding text
Absorbs the equivalent of about 2-3 super tampons worth of blood
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Thin, subtle, and designed to feel just like regular swimwear, in or out of the pool
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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, with a tampon or menstrual cup on heavy days or whatever works for your flow.

Other Features:
- Bum coverage: Max
- Wide waistband for comfort
- Mesh interior lining
- Super discreet liner

Pair with matching Double Scoop Bikini Top

MAIN BODY: 90% POLYESTER, 10% SPANDEX

MESH BRIEF: 86% NYLON, 14% SPANDEX

GUSSET LINING:  85% NYLON, 15% SPANDEX

GUSSET INTERIOR: FRESH FIX TECHNOLOGY®, 100% PU FILM


MACHINE WASH COLD, DO NOT BLEACH, DO NOT IRON, DO NOT DRY CLEAN, LAY FLAT TO DRY


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
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JUST PLAIN BETTER
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JUST PLAIN BETTER
Reviews
average rating 4.6 out of 5
Based on 31 reviews
  • 5 Stars
    24 Reviews
  • 4 Stars
    4 Reviews
  • 3 Stars
    2 Reviews
  • 2 Stars
    0 Reviews
  • 1 Star
    1 Review
94% of reviewers would recommend this product to a friend
Write a Review
Review posted
Reviewed by Clara L.
Verified Buyer
Period Swim Board Shorts
Reviewing
Period Swim Board Shorts
Rated 5 out of 5

Everything I was promised!

These shorts are SUPER comfortable and secure. I got them in Wave Pool and the color matches its online portrayal beautifully:) Can be worn with any assortment of swim tops or honestly as normal shorts as well. As someone who often feels insecure in swimsuits, these are a stylish relief to have in my wardrobe!!

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Review posted
Reviewed by Robyn W.
Verified Buyer
Period Swim Board Shorts
Reviewing
Period Swim Board Shorts
Height
5’6 – 5’8”
Size Purchased - Knixteen Underwear
M
Rated 5 out of 5

Perfect for water activities

Perfect for being active outside and doing water activities. Fit well, even on an adult. Slightly lower rise.

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I recommend this product
Comfort
Rated 4 out of 5
Fit
Rated 0 on a scale of minus 2 to 2, where minus 2 is Runs Small, 0 is True to Size and 2 is Runs Large
Effectiveness
Rated 4 out of 5
Ease of Use
Rated 5 out of 5
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Review posted
Reviewed by Jennifer H.
Verified Buyer
Period Swim Board Shorts
Reviewing
Period Swim Board Shorts
Height
5’6 – 5’8”
Usual Pant Size - Knixteen
Womens 10-14
Size Purchased - Knixteen Underwear
L
Rated 5 out of 5

My teen loves these!

We’ve bought these every year as she’s grown. She loves them and feels confident to swim every day of the month. I highly recommend!!

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I recommend this product
Comfort
Rated 5 out of 5
Fit
Rated 0 on a scale of minus 2 to 2, where minus 2 is Runs Small, 0 is True to Size and 2 is Runs Large
Effectiveness
Rated 5 out of 5
Ease of Use
Rated 5 out of 5
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Review posted
Reviewed by Kara
Verified Reviewer
Period Swim Board Shorts
Reviewing
Period Swim Board Shorts
Height
<5’5”
Size Purchased - Knixteen Underwear
L
Rated 5 out of 5

Exactly what I needed

I am almost 30 and was looking for something looser fitting for swimming so based on other reviews I figured I would try these and I was pleasantly surprised! I sometimes even just wear them around the house because they are comfy. Might be buying other colours. I am usually a medium but sized up to a large and they fit great

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I recommend this product
Comfort
Rated 5 out of 5
Fit
Rated 0 on a scale of minus 2 to 2, where minus 2 is Runs Small, 0 is True to Size and 2 is Runs Large
Effectiveness
Rated 5 out of 5
Ease of Use
Rated 5 out of 5
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Review posted
Reviewed by Tanya
Verified Buyer
Period Swim Board Shorts
Reviewing
Period Swim Board Shorts
Rated 5 out of 5

Perfect

Seeing as these are not offered in the womens line I took a chance an ordered. I'm 46 yrs old and wanted something more then a bikini bottom or cycling short for aquafit. I normally wear between a med/large and played it safe and ordered the xl. Now they do fit a little big but thankfully can tighten with the waist string and I only wear these on my light days cause I'm a little too self conscious on heavier days. But I absolutely love these shorts and wish they were around when I was a teen.

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