Best Sellers Carousel

What is your First Pair Risk Free for 30 Days Guarantee?

Leakproof Underwear, Risk Free

Trying leakproof underwear for the first time? Your first pair is completely risk free for 30 days. Wear them, wash them, and see how they work for your body. If they’re not right for you, we’ll refund your first pair. Prefer a different size or style? We also offer free exchanges.
How it works:
* Risk free applies to leakproof underwear on your first order
* Refund covers the item price (original shipping excluded)
* Just email info@knix.com and we’ll take care of you

Bundle & Save Offer - Terms & Conditions

*Offer valid on select underwear and thigh saver styles on knix.com and knix.ca, while supplies last. When you purchase three or more eligible styles you’ll receive the corresponding offers:
- Buy 3+ Save 15%
- Buy 5+ Save 20%
Exclusions: Sale & Last Call items
Discount is automatically applied at checkout and is based on eligible items in your order. No rain checks or price adjustments on previous purchases.

How do I find out my absorbency level?

Are Leakproof products tax-free?

Which styles have more front or back coverage?

Coverage at Knix comes in all shapes and sizes. If we’re talking about silhouettes, we go all the way from thongs to boxers.

We also offer high rise styles, like the Leakproof UltraThin No-Show High Rise, that sits just above the natural waist and gives full coverage through the stomach, hip & bum.

For extra liner coverage, look for undies that have an “extra-long liner” (usually 10”-14”), like in our Super Leakproof® Dream Short™ and our new SuperPlus Leakproof® Collection with our longest front-back-liner.

Have a suggested style or coverage? Just let us know. We love the feedback!

What can Leakproof underwear be used for?

What is Leakproof technology and how does it work?

What’s a gusset?

A gusset is the extra piece of fabric sewn into the crotch area of underwear.

It’s there to:
* Add comfort
* Improve fit and flexibility
* Provide breathability

For leakproof underwear, the gusset is especially important—it’s the absorbent, protective layer that helps trap and hold fluid.

Think of it as the functional core of the underwear: the part that does the real work.

Do I need to wear a pad or tampon with leakproof underwear?

Totally up to you. All of our absorbencies have been wear tested and lab tested, but some people prefer to wear one for their own comfort levels. Others have tried Leakproof Underwear throughout their cycle and know the right pair for every leak. Our advice? Do what makes you feel most confident.

How do I wash Leakproof underwear?

We designed our products to be super easy to wash and care for. For best results, rinse with cold water first, then machine wash on a cold cycle with mild detergent. It’s that easy! Different styles have different drying instructions, so always be sure to check.

Pro tip: Don’t use softener or bleach, and never iron.

How many pairs do I need for a period cycle?

That depends on you and your flow. And remember: everyone’s flow is different.

We suggest getting used to Leakproof Underwear like you would with any other leak protection. That might mean wearing your first pair at night or while you’re hanging out at home, just so you can get a better sense of your flow and your absorbency needs.

When you’re wearing your undies throughout your cycle, you can change them on your flow and the absorbency of the pair. For example, some people on their medium flow days wear one pair of UltraThin for their work day, then switch to another pair when they get home in the early evening.

For quick reference: Styles like our SuperPlus Leakproof® Underwear are great for your heaviest flows days. Our Light Leakproof No-Show Bikini, is a great option for those days of spotting and our Super Leakproof® No-Show High Rise is a great option for heavier days.

Bras

Underwear

Shop by Category

Trending

Shop by Style

Underwear by Solution

Bras

Solutions

Trending

Swim

Teen

Mens

Sale

Shop by Style

More Ways to Shop

Bras

Swim

Sale

Join Club Knix

Your Bag

Order summary

Suggestions

Top Picks

Revolution V-Neck Bra

Super Leakproof® Dream Short™

WingWoman Contour Bra

Leakproof UltraThin No-Show Bikini

Best Sellers Carousel

Super Leakproof® Mini Dream Boxer

Revolution V-Neck Bra

Super Leakproof® Dream Boxer™

Uplift Push Up Bra

Super Leakproof® Dream Short™

Leakproof Sculpt Classic One Piece Swimsuit

Leakproof UltraThin No-Show High Rise

Seersucker Sculpt Triangle Bikini Top

Seersucker Sculpt String Bikini Bottom

WingWoman Contour Bra

Leakproof UltraThin No-Show Bikini

FreeFlex™ Demi Bra

The Quintessential Sleep Set

The One&Only Scoop Bra®

Super Leakproof® No-Show Thong

Modal Rib T-Shirt

Light Leakproof No-Show Boyshort

Filters

Your underwear questions, answered.

What is your First Pair Risk Free for 30 Days Guarantee?

Bundle & Save Offer - Terms & Conditions

How do I find out my absorbency level?

Are Leakproof products tax-free?

Which styles have more front or back coverage?

What can Leakproof underwear be used for?

What is Leakproof technology and how does it work?

What’s a gusset?

Do I need to wear a pad or tampon with leakproof underwear?

How do I wash Leakproof underwear?

How many pairs do I need for a period cycle?

Shop by Category

Bras

Underwear

Swim

Sleep

New Arrivals

Best Sellers

Apparel

Active

Shapewear

Teen

Mens