Period Swim Bikini Bottom

Period? No problem. These bottoms let you swim with confidence, not discomfort. You can wear them alone or as backup protection to tampons and menstrual cups. Designed with three layers of 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 about the same as 1-3 regular tampons of period blood.

Layer 3: A waterproof outer layer prevents swelling.

Other Features:

- Classic bikini cut

- Bum coverage: Medium

- Super discreet liner

- 50+ UPF protection

- Pair with matching Double Scoop Bikini Top

Finally, a swim bottom you can cannonball in, even on your period.
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Image of a absorbancy surrounding text
Absorbs about the same as 1-3 regular tampons of period blood.
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Rapidly absorbs moisture to keep you fresh and dry.
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Thin, subtle, and designed to feel just like regular swimwear.
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Simply machine wash cold and lay flat to dry.

Period? No problem. These bottoms let you swim with confidence, not discomfort. You can wear them alone or as backup protection to tampons and menstrual cups. Designed with three layers of 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 about the same as 1-3 regular tampons of period blood.

Layer 3: A waterproof outer layer prevents swelling.

Other Features:

- Classic bikini cut

- Bum coverage: Medium

- Super discreet liner

- 50+ UPF protection

- 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: Fresh Fix 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
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COMFORTABLE
JUST PLAIN BETTER
Reviews
average rating 4.4 out of 5
Based on 141 reviews
  • 5 Stars
    107 Reviews
  • 4 Stars
    10 Reviews
  • 3 Stars
    6 Reviews
  • 2 Stars
    6 Reviews
  • 1 Star
    12 Reviews
84% of reviewers would recommend this product to a friend
Quality
Rated 4 out of 5
Comfort
Rated 4 out of 5
Effectiveness
Rated 4 out of 5
Sizing
Rated 0 on a scale of minus 2 to 2, where minus 2 is Fits Small, 0 is True to Size and 2 is Fits Large
Write a Review
Review posted
Reviewed by Cynthia A.
Verified Buyer
Period Swim Bikini Bottom
Reviewing
Period Swim Bikini Bottom
Height
5’9 – 5’11”
Size Purchased - Knixteen Underwear
XL
Rated 5 out of 5

Best fit ever

My teen continues to love these swim products! So easy to wash, perfect fit and material.

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I recommend this product
Comfort
Rated 5 out of 5
Fit
Rated -1 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 Eugenia S.
Verified Buyer
Period Swim Bikini Bottom
Reviewing
Period Swim Bikini Bottom
Height
<5’5”
Usual Pant Size - Knixteen
Kids 16-20
Size Purchased - Knixteen Underwear
M
Rated 5 out of 5

Runs small but nice

I had to order one size bigger because it runs small, but I love it!

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I recommend this product
Comfort
Rated 5 out of 5
Fit
Rated -2 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
Was this helpful?
Review posted
Reviewed by Cheryl A.
Verified Buyer
Period Swim Bikini Bottom
Reviewing
Period Swim Bikini Bottom
Band Size
N/A
Pant Size
Teen 00-2
Size Purchased
S
Rated 5 out of 5

Period Swim bottoms

The material is excellent and my daughter loves the cut and feel of these SWIM bottoms. She is 13 and wears size Small and it flatters her body. Now she can swim even on those "moon days!" True, it's not perfect because on heavy days some liquid runs down her leg but when that happens she has more reason to jump back in the lake!

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I recommend this product
Quality
Rated 5 out of 5
Comfort
Rated 5 out of 5
Effectiveness
Rated 5 out of 5
Sizing
Rated 0 on a scale of minus 2 to 2, where minus 2 is Fits Small, 0 is True to Size and 2 is Fits Large
Was this helpful?
Review posted
Reviewed by Mia F.
Verified Buyer
Period Swim Bikini Bottom
Reviewing
Period Swim Bikini Bottom
Height
<5’5”
Usual Pant Size - Knixteen
Womens 10-14
Size Purchased - Knixteen Underwear
L
Rated 5 out of 5

So comfy

Best swimwear ever

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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 4 out of 5
Ease of Use
Rated 5 out of 5
Was this helpful?
Review posted
Reviewed by Katrin H.
Verified Buyer
Period Swim Bikini Bottom
Reviewing
Period Swim Bikini Bottom
I'm a...
Parental Figure
I purchased for...
A Teenager/Tween
Current Band Size
28
Pant Size
Teen 00-2
Size Purchased
S
Usage
  • Beach
  • Pool
Rated 5 out of 5

THANK YOU!

My 12 year old daughter can now have a "normal" summer. I can't tell you how much of a relief it is to know that she can swim and have fun with her friends at any time of the month.

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I recommend this product
Quality
Rated 5 out of 5
Comfort
Rated 5 out of 5
Effectiveness
Rated 5 out of 5
Sizing
Rated 0 on a scale of minus 2 to 2, where minus 2 is Fits Small, 0 is True to Size and 2 is Fits Large
Was this helpful?