Knix vs Thinx Review: Which Period Underwear Is Better

Period underwear is quite popular lately. These washable and reusable pieces of underwear are meant to replace other uncomfortable disposable period products. But what piece of underwear is best?

Let’s find out.

In this review, I’ll analyze two quite popular period underwear brands – Knix and Thinx. I will analyze each one of them and then compare them head to head. After this review, you’ll know for sure which one is perfect for “that time.”

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Knix vs Thinx – Table Comparison

Before we start, here’s a quick overview of each brand’s main features.

Knix vs Thinx Period Underwear Comparison
High-quality period underwearYesYes
Sells other garmentsYesNo
Free shippingYes, on orders over $75Yes, for the first time. After that free shipping applies on orders over $99
ReturnsYes, on every product except underwear.Yes, on all products
Materials the gusset is made ofCotton, spandex, and carbonModal Cotton and elastane
Product variety22 different types of underwear categorized by absorbency19 different types of underwear categorized by collection and absorption level

Knix Review

Knix was founded in 2013 by Joanna Griffiths and is one of the fastest-growing direct-to-consumer brands in North America. Joanna’s vision was to create innovative period underwear that will empower women to live unapologetically free. Free from judgment. Free from self-doubt. And she did it.

She created an incredible line of most comfortable wireless bras and super-absorbent underwear, to make you feel more comfortable in your own skin.

Knix cares a lot about community as well. Their projects, Faces of Fertility and The Life After Birth Project are excellent examples of supporting and navigating people on one of the most important life journeys.


  • High-quality period underwear
  • Durable
  • Comfortable
  • Variety of products, colors, and sizes
  • Some items are great for everyday dry-wearing as well
  • Fresh Fix Technology
  • Super absorbent underwear can absorb up to 8 tsp of liquid.
  • The brand also sells regular undergarments and loungewear


  • Underwear is not eligible for a refund

Thinx Review

Thinx Inc. was founded in 2013 by Miki Agrawal, Radha Agrawal, and Antonia Dunbar. The brand has a very similar mission to Knix. Their vision was to find sustainable solutions to menstruation and incontinence. And just like Knix, they did.

Thinx makes comfortable underwear for every stage of your life – from period underwear & apparel for adults to period underwear for first and early periods. They also make underwear for bladder leaks as well.

Thinx cares about the environment as well. They make reusable period underwear in an effort to reduce plastic waste from disposables.


  • High-quality underwear
  • Brand cares about the environment
  • Made from eco-friendly cotton
  • Variety of products meant to replace tampons or pads
  • Free returns on all products
  • Free shipping on your first order regardless the amount


  • There was a conspiracy that Thinx underwear contained high levels of toxic chemicals

Knix Period Underwear Products

Knix Period Underwear is meant to fully replace tampons and pads. Knix Period Underwear pieces are comfortable, super absorbent, and machine washable.

The underwear is divided into two categories – Light to Medium Absorbency and Heavy to Super Absorbency. You can shop period kits as well as reusable pads.

Light to Medium Absorbency underwear absorbs the same as 1-3 tampons depending on style. This type of underwear is designed to protect you through your medium and light days, light leaks, and sweat.

Heavy to Super Absorbency underwear absorbs the same as 6-20 tampons depending on style. This type of underwear is designed to protect you through your heaviest days – and nights.

Knix offers a total of 11 different types of period underwear with light to medium absorbent properties as well as 11 different types of underwear with heavy to super absorbent properties.

Here are some best-selling pieces.

Leakproof High Rise Review

(Medium absorbency)

This high rise underwear features leakproof technology that absorbs up to 3 tsp of liquid. Leakproof High Rise Underwear is perfect for lighter days, as backup protection for the most intense days, or for dealing with light bladder leaks.

The body of the underwear is made of 77% nylon and 23% Lycra Xtra Life while the gusset lining is made of 86% cotton, 10% spandex, and 4% carbon. Leakproof High Rise underwear features Fresh Fix Technology – a wicking polyester layer that absorbs and traps moisture and a waterproof membrane to prevent leaks.

The underwear is available in 14 different colors and 8 sizes – XS – XXXXL.

Knixy Lace Leakproof Thong Review

(Light absorbency)

This leakproof thong looks so good you’ll want to wear it every single day. Knix ultimate leakproof technology absorbs up to 1 tsp of liquid while ultra soft and stretchy laces provide comfort and give you confidence. Knixy Lace Leakproof Thong is perfect for light days or as backup protection on heavy days. Basically, you can wear them every single day since they’re sooo comfortable. Plus you can wear them during your intense workout since they’re invisible under your leggings.

The body of the thong is made of 73% nylon and 27% spandex jersey. The lace is made of 90% nylon and 10% spandex. Speaking of the gusset, it’s made of 86% cotton, 10% spandex, and 4% carbon.

Just like Leakproof High Rise, Knixy Lace Leakproof Thong features Fresh Fix Technology.

Super Leakproof Boyshort Review

(Super absorbency)

Super Leakproof Boyshort is part of the most absorbent period underwear ever! The underwear absorbs up to 8 tsp and with an extended gusset, it will protect you every day of your cycle.

This underwear consists of a body and 4 gusset layers.

The main body is made of 70% nylon and 30% spandex. The top layer has moisture-wicking and anti-odor properties and it’s made of  84% Modal, 8% seaweed, and 8% spandex. The 2nd layer is an absorbent one and it is made of 100% polyester. The 3rd one is made using, already mentioned, Fresh Fix Technology, while the 4th one acts as a Waterproof Membrane made of polyurethane film.

Thinx Period Underwear Products

Thinx Period Underwear, just like Knix Period Underwear is meant to fully replace tampons and pads. Thinx Period lingerie is machine washable, and have built-in protection as well as odor-controlling properties.

On Thinx online shop, you can shop for your underwear by collections or absorbency. There are three Thinx underwear collections – Classic, Modal Cotton, and Thinx Air and five absorbency levels.

Let’s check out the best-selling ones.

Modal Cotton Bikini

(Moderate absorbency)

Modal Cotton Bikini is a comfy piece of period underwear made from eco-friendly Modal Cotton. It features leak protection and it’s super soft and breathable.

You should wear Modal Cotton Bikini underwear on moderate flow days and you will feel as comfy as in your favorite sweatpants. This type of underwear holds liquid as three regular tampons.

The body of Modal Cotton Bikini is made of 53% SUPIMA cotton, 35% TENCEL modal, 5% elastane 16% elastane. The 1st layer of the gusset is a wicking one and it’s made of 95% cotton and 5% elastane. The 2nd gusset layer is absorbent and it’s made of 96% cotton and 4% elastane. The last, 3rd one acts like a barrier and it’s made of 100% polyester.

Thinx Thong Review

(Lightest absorbency)

This minimal-coverage type of period underwear is made for your lightest days. It holds the amount of liquid as one regular tampon therefore it would be best to use it at the end of your period, or as a backup layer of protection with tampons or a cup.

Thong comes in three gusset layers, as well. The main body is made of 84% polyamide and 16% elastane, while the body liner is made of 95% cotton, and 5% elastane.

The 1st gusset layer has wicking properties and it’s made of 95% cotton and 5% elastane.

The 2nd one is absorbent and it’s made of 96% cotton and 4% elastane, while the 3rd one acts like a barrier and it’s made of 100% polyester.

Thinx Super Modal Cotton Brief Review

(Super absorbency)

This comfy, full-coverage underwear holds five regular tampons’ worth. Made of eco-friendly Modal Cotton Super Modal Cotton Brief is perfect for your heaviest days or overnight for maximum leak protection. Besides protection, Modal Cotton provides a cozy and buttery-soft feeling.

The body is made of 53% SUPIMA cotton, 35% TENCEL modal, 5% elastane 16% elastane. All three gusset layers are 100% polyester. Just like with other Thinx models, the 1st layer has wicking and the 2nd one has absorbent properties. The 3rd one acts like a barrier.

Knix or Thinx? Head to Head Comparison

As you could notice, both brands make incredible, high-quality period underwear. Let’s compare them head to head in terms of safety, comfort, variety, shipping, and exchange/return policies.

First, the most important one – which one is safer?

Knix lingerie isn’t chemically improved in terms of absorbance. They are made of cotton, spandex, and carbon. They also have tiny holes for better absorbent properties.

Speaking of Thinx, there was some controversy about the material Thinx underwear is made of. Allegedly, a scientist who recently tested pairs of menstrual underwear found that they contained high levels of toxic chemicals. On the other hand, Thinx has done recent independent testing of their products that seems to indicate that they are safe.

I’d go with Knix in this one.


Both Knix and Thinx are super comfy considering they are period underwear. However, people at Knix truly did their best to make the underwear as comfortable as possible. So the bottom line is, both brands make super comfy lingerie, but the ones made by Knix are comfortable even during dry-wearing.


Considering what I’ve just mentioned above, I’d go with Knix since they got me covered no matter what I need.

Knix isn’t focused on period underwear only. The brand also sells regular undergarments and loungewear. Speaking of the products meant to replace your pads or tampons, Knix offers leakproof panties, pads, leggings, shorts, and swimwear.

Thinx is, on the other hand, focused on period underwear and garments only. The brand offers  period panties, shorts, and leggings.

Shipping and Returns

Knix offers free shipping on orders above $75. If you’re unhappy you can return your item and you’ll get a full refund. However, this applies only to items eligible for a refund. Underwear items are not eligible for a refund, however, you can exchange them for another size, style, or store credit.

Knix offers international shipping as well. It’s free on orders above $150.

Speaking of Thinx, the company offers a 45-day free trial period on ALL products. So, if you receive your period-absorbing underwear and you’re not happy, you can request a refund or an exchange.

In terms of shipping, you’ll get free shipping on your first order however, after that you will get free shipping only on orders above $99.

As you could notice, Thinx has better shipping and return policies.

Knix vs Thinx Period Underwear – The Verdict

The fact is that both Knix and Thinx changed things when it comes to our period. By getting your period underwear you can go shopping without being afraid to stand up after sitting in a coffee shop for some time. That feeling is priceless.

If you want me to be picky and look both brands under the microscope, I’d tell you that Knix is a better option here. It’s less expensive, more comfortable (even when you’re dry-wearing them), and safer. Both brands offer so many different options when it comes to different types, sizes, and colors of your new period underwear. Knix even offers regular undergarments and loungewear.

I’m doing my best to disregard the rumors that Thinx is using some toxic chemicals to improve absorbency but it is still hiding somewhere deep in my mind.

The bottom line is, our period shouldn’t be taboo. It’s shouldn’t be any kind of kinky topic, therefore thank you Knix and Thinx for making our lives at least a bit more relaxed.

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