Leakproof Bikini

A classic seamless bikini with our patented, 3-layer leakproof technology built in.

First layer: Moisture-wicking, antimicrobial technology wicks away sweat and moisture while neutralizing odors to keep you fresh all day long. 

Second layer: A super thin, highly-absorbent liner that holds the power of 3 tampons or pads.

Third layer: A secure, liquid-resistant outer layer keeps leaks from happening. 

like your comfiest underwear, but with the power of 3 tampons.
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Holds up to 3 tampons or pads worth of blood.
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Thin, subtle, and designed to feel just like regular underwear.
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Rapidly absorbs moisture to keep you fresh and dry all day.
Antimicrobial layer kills bacteria and neutralizes smells.

A classic seamless bikini with our patented, 3-layer leakproof technology built in.

First layer: Moisture-wicking, antimicrobial technology wicks away sweat and moisture while neutralizing odors to keep you fresh all day long. 

Second layer: A super thin, highly-absorbent liner that holds the power of 3 tampons or pads.

Third layer: A secure, liquid-resistant outer layer keeps leaks from happening. 

Body: 77% Nylon, 23% LYCRA®

Gusset Liner: 86% Cotton, 10% Spandex, 4% Carbon

Gusset: Leakproof Technology


Free from PFAS and other chemical treatments.

Machine wash cold with mild detergent, do not bleach, lay flat to dry.

All sale items are Final Sale and cannot be exchanged or refunded.

For all other purchases, we can’t accept exchanges or returns on used items BUT you can try your first pair on your first order, risk-free! 

What’s First Pair Risk-Free?

If your first order includes multiple period underwear: OPEN, WASH & WEAR ONE PAIR ONLY to test them out. That way, in the unlikely event that you don’t love them, any unopened packages from the same purchase can be exchanged or refunded back to you within 30 days of delivery (excluding original shipping fees). All unopened packages will be donated to local organizations to support people in need.

We ship our items via DHL or Canada Post depending on your location. Please allow up to 10 business days for your items to be processed and shipped.

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.

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FOR THIS GENERATION
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for the planet!
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FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
Image of a chrome heart surrounding text
FOR THIS GENERATION
Image of a chrome heart surrounding text
for the planet!
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FOR THIS GENERATION
nothing is tmi here—we promise.
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Super Absorbency

Absorbs up to 12 tsp (60 ml) of blood—that’s about 12 regular tampons or pads! Perfect for overnight protection or on your heaviest days when changing into a fresh pair might not be convenient.

High Absorbency

Absorbs up to 4-8 tsp (20-40 ml) of blood or the equivalent of 4-8 tampons or pads. These are perfect for heavy flow days.

 Medium Absorbency

These absorb approximately 3 tsp (15 ml) or about 3 tampons or pads worth of blood! Ideal for light to medium flow days or as backup to tampons or period cups.

All of our period underwear, swim, and activewear have our patented, 3-layer leakproof technology built right in

First layer: moisture-wicking, antimicrobial technology wicks away sweat and moisture while neutralizing odors to keep you fresh all day long.

Second layer: a super thin, highly-absorbent liner that holds the power of 3-12 tampons or pads.

Third layer: a secure, liquid-resistant outer layer keeps leaks from happening.

The short answer: nope! Depending on the level of absorbency of leakproof period underwear you choose and the heaviness of your flow, you can wear our period undies on their own or as backup protection along with a pad or tampon. You're totally protected with our high and super absorbency leakproof underwear, while our low and medium absorbency leakproof underwear can replace pads and tampons on lighter days and work great as a backup to whatever youre already using on heavier days.

Do a quick rinse before you throw your underwear in the machine. Wash on cold with mild detergent then tumble dry on low. That's it! Be sure not to use softener or bleach and never iron... Not that you would.

If you’re not sure which size underwear to get, just book a Virtual Fitting and someone from the Knix team will video chat you to walk you through everything!

Because they're, well, underwear we can't accept exchanges or returns on used items but you can try your first-pair on your first order, risk-free!

How it works:

if your first order includes multiple period underwear: open, wash & wear one pair only to test them out. That way, in the unlikely event that you dont love them, any unopened packages from the same purchase can be exchanged or refunded back to you within 30 days of delivery (excluding original shipping fees).

All unopened packages will be donated to local organizations to support people in need.

*All sale items are final sale.

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Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Image of a chrome heart surrounding text
Comfortable
Image of a chrome heart surrounding text
Sustainable
Image of a chrome heart surrounding text
Absorbent
Reviews
average rating 4.8 out of 5
Based on 1363 reviews
  • 5 Stars
    1138 Reviews
  • 4 Stars
    173 Reviews
  • 3 Stars
    26 Reviews
  • 2 Stars
    7 Reviews
  • 1 Star
    19 Reviews
97% of reviewers would recommend this product to a friend
Quality
Rated 4 out of 5
Comfort
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
Effectiveness
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
1363 Reviews
Reviewed by Angie C.
Verified Buyer
I recommend this product
Rated 5 out of 5
Review posted

Great panties - message needs amending

My daughter has not yet stated her period but I got these for her and me to try out, continue communication and to be prepared. They are super comfortable and look great. Leakage yet to be tested.

I would seriously urge you to consider amending the wording on the packaging though - using ‘the curse’ is way too negative and dated, even if it’s intended to be humorous. We really need to counter negativity about girls and women’s bodies and ensure the language is positive, empowering and celebratory.

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Reviewed by Claudia C.
Verified Buyer
I recommend this product
Rated 5 out of 5
Review posted

Great company /great customer service

I ordered one pair of underwear for my daughter. She wore and after a few hours she said they were comfortable so I ordered several more...$85.00 worth. I should have known better because she’s super sensitive and sure enough the next time she wore them she had complaints. I don’t think there was really anything wrong with the product she’s just really picky and I just think they weren’t a perfect fit for her. So a few days later the $85 order arrived. I didn’t open it and just contacted Knox about a return. They immediately gave me a refund without our me even returning all of the underwear. Then they sent me a really nice email saying that they gave me the 85 refund but that I could KEEP all of the products and give them to someone else or donate them to a women’s shelter. How nice is that?! Not many companies would do that. I’ll definitely be donating them my local women’s shelter.

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Reviewed by Rachel R.
Verified Buyer
I recommend this product
Rated 5 out of 5
Review posted

perfect for workouts

I’m not a teenager, but rather a smaller adult (late 30s) and I love these for everyday wear. I am super picky, and these are comfortable and perfect for workouts. Pay attention to the size chart, because it isn’t the same as standard girls OR women’s sizing. I normally wear a girls 14-16 or women’s 00-0 bottoms and a M fits perfectly.

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Reviewed by Morgan
I recommend this product
Rated 5 out of 5
Review posted

Worth it

I’m 22, 5’7 and weigh 120lbs. Up until now, I have been purchasing size Small on the Knix womens website. The M teen fits exactly the same and are SO much more cost effective. Bought the 5-pack of course! Hope to see more styles in the future (please make a Knixteen thong!)

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Reviewed by Happy Mama :.
Verified Buyer
I recommend this product
Rated 5 out of 5
Review posted

She loved them

My 13 year old daughter started her period this week and I just wanted to say how much she loved the underwear! I’m so happy that I purchased them a couple of months ago and had them ready for her first time. They made the day a whole lot easier.

She’s always had sensory issues and has dermatographia (hives if her skin is scratched) and was very relived to find that they were soft and didn’t irritate her skin.

She was nervous about going to school for the first time, but wearing these helped ease her anxieties and made her feel a lot more confident. They were a perfect fit under her dance leotard too :)

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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
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