Saalt vs. Knix: Menstrual Cups or Period Underwear?

Key Takeaways:

• Category Focus: Saalt focuses on menstrual cups, discs, and leakproof underwear, emphasizing sustainability and period equity, while Knix offers period underwear alongside a broader range of intimates and activewear.

• Protection Differences: Menstrual cups provide high capacity and long-lasting protection but require a learning curve, whereas period underwear offers ease of use and versatility but may need frequent changes on heavy days.

• Safety & Sustainability: Saalt's commitment to safety and sustainability is evident through its use of medical-grade silicone and B-Corp certification, while Knix focuses on reusable solutions and ethical sourcing without B-Corp status.

Hey there! Let’s open up some conversation about finding the best solution for your period, postpartum, or those unpredictable bladder leaks—should you go with a Saalt menstrual cup or Knix period underwear? Both have changed the game for people who want comfort, confidence, and fewer “uh-oh!” moments.

Menstrual cups and discs like Saalt’s are reusable, eco-friendly, and can be worn for up to 12 hours, making them budget-friendly over time. They’re great if you want to “set it and forget it,” whether you have a heavy flow or just want the freedom to swim, hike, or chase after kids without worry. Plus Saalt retails leakproof undewear with the thinnest and driest gusset on the market. With Saalt’s lineup of fully sustainable options, your entire period is completely covered from beginning to end. Plus, Saalt is a B-Corp committed to sustainability, donating 1% of revenue to period equity programs.

On the other hand, Knix only retails period underwear and other intimates, like bras. They are sleek, comfy, and mess-free. Just slip on a pair and go—no insertion, no learning curve. They’re perfect for light to medium days, for backup protection, teens, or if you simply can’t do internal products.

The ultimate brand choice comes down to your comfort and convenience. Cups require a bit of practice but reduce waste and cost. Underwear is worry-free and simple to use, especially on lighter days or for extra security. (Cleveland Clinic)

No matter what you pick, both Saalt and Knix aim to leave you feeling empowered and leak-free through every stage of life—so you can say goodbye to tying sweaters around your waist and living life on your terms.

Quick Brand Overview: Saalt vs Knix

Let’s break down these two top brands in the reusable period care space. Saalt is known for its premium menstrual cups, discs, and patented leakproof period underwear. Their mission: make periods easier, environmentally friendly, and help global period equity through B-Corp certification and donations. Their underwear comes in different absorbencies, styles, and sizes—think comfort for teens, postpartum moms, and anyone needing incontinence support with bladder leak underwear.

Knix, in contrast, has made a name with leakproof period underwear, but also serves a wider market with activewear, bras, and shapewear. Their period products earn praise for absorbency and sleek design, catering to people who want to ditch disposables and stay comfortable, but their broader lineup means their focus is spread out.

Both Saalt and Knix offer leakproof, reusable alternatives to pads and tampons, and are committed to sustainability and comfort. Saalt leans into a mission-driven, specialized approach, while Knix casts a wider net across intimates and activewear. It’s like choosing between a deeply focused RPG or a multipurpose open-world game—both are strong picks, so it’s about what fits your lifestyle best.

Absorbency and Leak Protection Showdown

When managing periods or light bladder leaks, absorbency and leak protection are the top priorities. Period cups and menstrual discs are famous for high capacity—most hold between 25 and 50 ml, equal to several tampons’ worth. With a good seal and proper fit, they can offer up to 12 hours of reliable, leak-free protection, even on heavy days. However, if the fit isn’t perfect or insertion isn’t right, leaks can occur, requiring some trial and error for optimal comfort and security.

Period underwear takes a different approach, using multi-layered fabrics for moisture-wicking and waterproof protection. Many brands can handle a light to moderate flow, and some absorb as much as 7-10 tampons. They’re simple to use—just slip on and go—with no insertion and little learning curve. However, once they reach their absorbency limit, you’ll need a spare pair handy, particularly on heavy days. Unlike cups, you can’t “empty” them while out and about.

So, which wins? The answer depends on your needs. Menstrual cups and discs are great for heavy flows and long stretches without a bathroom break, provided you nail the fit. Leakproof panties excel in comfort and accessibility, perfect for lighter days, overnight use, or as backup for another product. It’s less about which is “better” and more about which fits your lifestyle—whether you’re powering through a busy day or wanting worry-free coverage for lounging at home.

Materials, PFAS, and Safety Standards

When it comes to menstrual cups and period underwear, knowing what’s in your products is essential for both safety and comfort. Saalt menstrual cups are made from medical-grade silicone—known for being non-porous, hypoallergenic, durable, and easy to sanitize. However, not all silicone is equal, and some brands aren’t always transparent about sourcing or additives, leaving uncertainty for consumers. Learn more about how to insert a menstrual cup. 

Period underwear, meanwhile, uses a layered construction: a soft, moisture-wicking top (like cotton or bamboo), an absorbent core (often synthetic blends), and a leakproof barrier. Here’s the concern—some leakproof barriers can contain PFAS, the so-called “forever chemicals” associated with health and environmental risks. Even trace PFAS levels in some period underwear have raised alarms, especially when brands are vague about materials or testing. (Technology Networks)

Menstrual cups generally avoid this issue if they’re pure silicone, but ingredient transparency is essential. The best brands don’t just meet basic regulatory standards like FDA or EU approval—they opt for third-party testing and provide clear, honest ingredient lists, so users aren’t left guessing about product safety.

Sustainability also matters. Menstrual cups and reusable menstrual discs are designed for years of use, significantly reducing waste. Quality period panties can also be reused for years if made well and free from harmful chemicals. However, if those products contain substances like PFAS, their environmental and health impacts are questionable. The most responsible companies make every effort to choose safe, sustainable materials from start to finish—because everyone deserves products that are good for their bodies and the environment.

Comfort and Fit for Every Body Type

Comfort is the true MVP of any period product, especially for anyone managing postpartum recovery, an active lifestyle, or the changes that come with age. The right fit means freedom from distraction—no leaks, no chafing, and no bulk.

Menstrual cups, when sized properly and inserted correctly, can feel invisible. They adapt to your unique shape and don’t have the bulk or irritation of pads or the string of a tampon. Many brands offer a variety of sizes, including teen period cups and even soft cups. However, their learning curve is real—mastering the right fold and positioning is essential, especially after pregnancy or physical changes with age. But once you’ve figured it out, menstrual cups can be incredibly convenient, especially for long, unpredictable days.

Period underwear, by contrast, offers grab-and-go comfort straight from your drawer. High-quality postpartum underwear features breathable, flexible fabrics that adapt to your body, making it a comfortable choice for postpartum recovery, busy days, and light leak protection. From high-waisted silhouettes for support to bikinis for everyday use, you’ll find a variety tailored for different shapes. The secret is a well-designed, wide gusset that protects you without feeling bulky or diaper-like. These styles are crafted for that barely-there feel, so you can focus on your day, not your period.

Both menstrual cups and period underwear offer inclusive sizing and comfort for every stage of life—from teens figuring out new routines to adults managing changes. Always prioritize products that adapt to your body, not the other way around. Comfort isn’t a luxury; it’s essential for building confidence and living your life uninterrupted.

Sustainability Credentials and B-Corp Impact

When choosing between menstrual cups and period underwear, sustainability is key. Some brands have gone all-in on eco-conscious design, crafting products free from harmful chemicals like PFAs, and putting an emphasis on reducing waste. Their leakproof products offer comfort—and peace of mind that you’re making a planet-friendly choice. Many are B-Corp certified, meaning they’re rigorously assessed for social and environmental standards, transparency, and accountability. For some brands some of their revenue goes directly to supporting global period equity initiatives, providing access to menstrual products in underserved communities. 

This ensures your purchase supports positive change far beyond your own needs.

Competitors also strive for sustainability, focusing on reusable, durable period care solutions that help keep disposable pads and tampons out of landfills. Their emphasis on longevity means fewer replacements, and many use ethically sourced materials. While not all have B-Corp status, several maintain eco-focused partnerships and educational programs about sustainable period care, driving awareness and responsible consumption.

So, if you want your purchase to make an impact, both menstrual cups and period underwear offer strong sustainability stories. Whether you value globally certified impact and outreach, or prioritise innovation in reuse and waste reduction, there’s a brand out there aligning with your values. The choice isn’t about picking a clear “winner”—it’s about supporting the mission that speaks to you as you consider your best sustainable period care option.

Making the Choice: Saalt or Knix?

When deciding between Saalt and Knix, you’re not just picking a product—you’re choosing a lifestyle shift. Saalt’s leakproof underwear, crafted without harmful PFAs, offers a range of absorbencies and styles to fit every phase of life—from teens to golden years. As a B-Corp, we’re obsessed with sustainability and donate 1% of revenue to period equity initiatives worldwide. Saalt isn’t just about catching leaks; it’s about ending the panic, the waist-tied sweaters, the towel-strewn beds. We’re here for premium, reusable solutions that don’t break the bank. 

Knix has its merits, especially if you’re drawn to their underwear-first approach. But if you want a brand that’s got your back (and your front) through every leak life throws at you, Saalt’s mission and products speak louder. Make the switch. Join us in rewriting the rules of periods and leaks—one comfortable, confident day at a time.

Read Also:

• Period Care Showdown: How Menstrual Cups and Period Underwear Stack Up Against Pads and Tampons

• Why Menstrual Cups, Discs, and Period Underwear Perform Well for Athletes

• Why Period Underwear and a Menstrual Cup Are a Sustainable Match Made in Heaven

FAQs About Saalt vs. Knix: Making the Right Choice for Your Period Needs

What is the main difference between Saalt and Knix products?

Saalt and Knix both tackle leaks, but their focus differs. Saalt specializes in reusable menstrual cups, discs, and leakproof underwear, all made with sustainability, comfort, and safety in mind. Saalt’s products are manufactured without harmful PFAs and are suitable for a wide range of users—from teens to postpartum moms. Knix focuses mainly on period and leakproof underwear, prioritizing absorbency and convenience. If you want a broader range of reusable solutions, including internal options, Saalt is your go-to. Both brands are committed to comfort and eco-consciousness, but Saalt adds an extra layer of advocacy and certification as a B-Corp.

Which is more comfortable: Saalt menstrual cups or Knix period underwear?

Comfort depends on your preferences and routine. Saalt period cups and period discs, made from soft medical-grade silicone, offer an internal, barely-there feel once properly inserted—ideal if you want a long-wear, hands-off option. Saalt’s leakproof underwear has a patented gusset guaranteed to be the thinnest and driest leakproof panties on the market. Knix period underwear are a great option with built-in absorbency for external protection, which is great if you dislike internal products. If you want a subtle, all-day solution and don’t mind insertion, Saalt cups often deliver. If you want something familiar and external, Knix or Saalt underwear are both comfy choices.

Are Saalt menstrual cups and discs safe to use?

Yes! Saalt menstrual cups and discs use 100% medical-grade silicone, free from BPA and toxins. They are extensively tested to ensure safety and body-friendliness, whether you’re new to cups or returning postpartum. Proper cleaning—like boiling between cycles—keeps them hygienic and durable for years. Saalt’s commitment to safe, sustainable period care means your health comes first. Learn how to sanitize your menstrual cup. 

How long can you wear a Saalt cup compared to Knix underwear?

Saalt cups and discs deliver up to 12 hours of protection before needing to be emptied and rinsed—perfect for overnights or busy days. Knix and Saalt underwear also offer around 8-12 hours of protection, but exact duration depends on absorbency and flow. On heavier days, leakproof underwear may require a change, but Saalt cups and discs tend to offer longer, uninterrupted wear since they hold more fluid. For long-lasting, all-day security, Saalt menstrual cups and discs often have the edge.

Which is better for heavy flow: Saalt or Knix?

For heavy flow, Saalt’s menstrual cups and discs are standouts—holding up to 6 tampons’ worth of blood. They’re ideal for postpartum or anyone with intense cycles, and perfect for extended wear. Knix and Saalt underwear might handle up to 7-10 tampons' worth of flow, so for very heavy days, you might consider doubling up with an inserted product like a cup or disc and using backup period pants for solid protection. 

Sources:

1. Cleveland Clinic. (2025, November 17) Everything You Need to Know About Menstrual Cups. https://health.clevelandclinic.org/menstrual-cup

2. Technology Networks. (2025, July 22) Toxic PFAS Found in Reusable Menstrual Products. https://www.technologynetworks.com/applied-sciences/news/toxic-pfas-found-in-reusable-menstrual-products-402586#:~:text=Reusable%20menstrual%20products%20are%20marketed,reusable%20menstrual%20and%20incontinence%20products.