KT by Knix | Period Underwear, Swim & Activewear for Teens

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★★★★★ 100K+ 5-star reviews & counting

Protection you can rely on.

Swim without the period stress Swim without the period stress

Never miss out on fun in the water, no tampons needed! Get the period swim teens love and parents trust in brand new styles and prints.

Shop New Swim How Leakproof Works

“My daughter had a seamless first period with her Kt underwear (I'm not crying, you're crying).”

-Jordan R., Verified Buyer, Super Leakproof® No-Show Boyshort

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“Worked perfectly! As expected, she got her period 1/2 way through camp. She said she spent every day in the lake without a worry!”

-Lori S., Verified Buyer, Period Swim Sport One-Piece

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“These shorts are so comfortable to sleep in! The extra long built in pad saved me from leaking. I could finally sleep comfortably on my period.”

-Linda P., Verified Buyer, Super Leakproof® Sleepover Short

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“These undies are the easiest for my tween to use; she likes them way better than pads or tampons. And I love that they're a reusable product.”

- Allison B., Verified Buyer, Leakproof UltraThin No-Show Boyshort 3-Pack

Shop Period Undies

LOVED BY TEENS. TRUSTED BY PARENTS.

Why leakproof?

Built-in protection that helps teens feel secure on their period. The science behind the #1 Leakproof Brand in North America.

Soft top layer

Comfy, super smooth moisture-wicking liner keeps you feeling fresh and dry.

Middle absorbent layer

Bottom leakblocker layer

How to wash

Why I started KT By Knix

Kt was founded in 2017 because we believe every teen deserves period products that make them feel as confident as possible.
‎

Joanna, Founder of KT by Knix

Learn More

Your leakproof questions, answered.

What is Leakproof underwear and how does it work?

What do the different underwear absorbency levels mean?

Heavy Absorbency

Absorbs about the same as 4-7 super tampons. Perfect for overnight protection or your teens heaviest days when changing into a fresh pair might not be convenient.

Moderate Absorbency

Absorbs about 2.5 super tampons' worth of blood. Ideal for medium period days, discharge and sweat.

Light Absorbency

Absorbs about the same as about 1 regular tampon worth of blood, sweat or discharge. Ideal for lightest period days, spotting, sweat and discharge.

Are Leakproof products tax free?

Good news, period underwear and pads are exempt from federal sales tax in Canada, and most provincial/harmonized sales taxes too. The exception? If your order ships to (or you're shopping in a store in) British Columbia or Manitoba, a 7% PST applies. Saskatchewan, it's 6% PST. Still have questions? We've got more info here.

How do I wash period underwear?

It's easy, we promise. Give them a quick rinse under cold water first, then toss them in the washing machine with your regular clothes, cold water, mild detergent, no softener or bleach. For drying: lay flat for medium absorbency styles, or tumble dry on low for high and super absorbency ones. That's it. No ironing needed!

Does my teen need to wear a pad or tampon with period underwear?

Totally up to them! Every flow is different, and there's no wrong answer. Depending on the absorbency level and how heavy their period is, they can wear KT undies on their own or use them as backup alongside a tampon or menstrual cup. Whatever makes them feel most confident is the right call.

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