Everything You Need to Know About joni Period Underwear

What Is Period Underwear, and Why Is It Actually Different?

Let's start with the basics. Period underwear looks like regular underwear—because it is. The difference? Built-in absorbent layers in the gusset catch and hold menstrual fluid without any external products.

Think of it as the bridge between traditional pads (which feel restrictive) and tampons (which can dry you out and carry risks that aren't talked about enough). Period underwear lets you move through your day without thinking about your period—not because you're suppressing it, but because your protection is actually integrated into what you're already wearing.

You can go to the gym in it. Sleep in it. Wear it under literally anything. And it actually stays in place, moves with you, and doesn't slip or bunch.

But here's what makes joni's period underwear different: we didn't rush it. We took time getting the science, materials, and design exactly right. And we did it with the same commitment to transparency, sustainability, and equity that defines everything joni makes.

Why joni Started with Disposables (And Why That Matters)

joni launched in March 2020 with one mission: make it possible for everyone who bleeds to access sustainable period care—because period care is a human right, not a privilege.

We started with disposable organic pads and tampons. Here's why that choice matters:

🩸 Accessibility means meeting people where they are. Disposables have the lowest barrier to entry—lowest cost, no learning curve, no upfront investment. By focusing on making sustainable disposables first, we reached hundreds of thousands of menstruators. Since 2020, we've donated over a million joni products to communities in need through our 2% giveback promise.

Our mission was always bigger than pads and tampons.

How joni Period Underwear Actually Works

Let's get into the details, because they matter.

Coverage That Actually Covers

Most period underwear covers the crotch area. joni's design runs 360 degrees—from the front waistband all the way to the back top. This isn't a design detail we're bragging about just to brag. It's functional.

When you're sleeping, moving, bending, sitting, stretching—your body is shifting. Coverage that only covers the front or centre? It moves with you, and gaps open up. joni's full-coverage design moves with your body. No shifting. No leaks from unexpected angles. This is especially crucial if you have a heavier flow or if you sleep on your side or stomach.

Absorbency: What "40ml" Actually Means

joni period underwear holds 40ml of fluid—equivalent to roughly 8 hours of protection on an average flow day, or 4 regular tampons.

If you have a light to moderate flow, this might be your all-day solution. If you have a heavier flow, you might pair it with other products, or you might change more frequently. (And that's okay—the goal is finding what works for your body, not fighting your body.)

We're transparent about absorbency because we hate vague marketing language. You deserve to know what you're getting.

The Material Science Behind joni Period Underwear

We could tell you our underwear is made with soft, thoughtfully sourced fibres and leave it at that. But that's not radical transparency—that's marketing. So let's go deeper.

From Fibre to Fabric

joni Leakproof Period Underwear starts with a lyocell and cotton blend, with a 100% merino wool lining where it matters most. Each material has a job to do: feel incredibly soft, breathe, manage moisture, and perform through periods, leaks, washes, and real life.

Let's start with lyocell.

Lyocell begins with wood pulp from responsibly sourced trees. The pulp is dissolved into a solution and spun into smooth, soft fibres using a closed-loop manufacturing process. That means the solvent used to create the fibre is captured and recycled back through production rather than continuously being discarded.

The result? A fabric that's exceptionally soft, breathable, and comfortable against your body—without relying on virgin polyester to get there.

Then there's the part that sits closest to your skin: our 100% merino wool lining.

Merino is nature's performance fibre. Its unique structure helps move moisture away from your skin, regulate temperature, and naturally manage odour. It's soft, breathable, renewable, and biodegradable—and it gives us high-performance next-to-skin comfort without a synthetic lining. Dive deeper into how merino wool levels up the period underwear experience.

Together, lyocell, cotton, and merino wool create period underwear that feels less like a period product and more like really, really good underwear.

Because what touches your body matters. And being transparent about how it's made matters, too.

TPU Gusset: Breathable, Flexible, Leakproof

The absorbent layer in the gusset uses TPU (thermoplastic polyurethane)—a material specifically chosen because it:

• Breathes, so your skin isn't trapped in plastic

• Flexes with your body, so it moves instead of restricting

• Blocks leaks without feeling rigid or uncomfortable

• Is tested to be PFAS-free (more on that below)

PFAS-Free: What That Actually Means and Why It Matters

You have valid questions about what’s in the products you wear close to your body. We do, too.

But “chemical” doesn’t automatically mean dangerous. What matters is what the substance is, how much is present, and how you're exposed to it. In toxicology, dose matters: many substances can be safe at one level and harmful at another.

PFAS deserve particular attention because some can persist in the environment and accumulate over time. They’ve also been used in water- and stain-resistant textiles—which makes asking about them in leakproof period underwear completely reasonable.

PFAS stands for per- and polyfluoroalkyl substances—essentially, forever chemicals that don't break down in the environment or in your body. They accumulate over time. They're linked to health impacts including fertility issues, immune suppression, and hormone disruption.

That’s why we don’t ask you to take our word for it. joni Leakproof Period Underwear is independently tested for PFAS and other substances of concern, so we can verify what’s in the finished product you actually wear.

Because transparency shouldn't make everything sound scary. It should give you the information you need to make an informed choice.

How to Care for Your joni Period Underwear (It's Easier Than You Think)

Here's where reusable period products can trip people up: if the care is complicated, people don't use them. They sit in a drawer, and you're back to buying disposables.

We designed joni period underwear to be actually easy to care for.

The Basic Routine

Wash: Throw your period underwear in your regular laundry on a normal cycle, in cold water. You don't need special detergent. You don't need a delicate cycle (unless you're delicate with all your underwear). 

NOTE: If you're not washing straightaway, rinse your used period underwear with cold water, which prevents blood from setting into the fabric.

Air dry: Skip the dryer. Heat can damage the TPU gusset over time. Hang dry. In a typical bathroom or bedroom, they'll dry overnight.

That's it. No complicated rituals that make reusables feel like a second job.

Who is joni Period Underwear For?

Here's the real question: is this for you?

Sizing and Styles

joni period underwear comes in:

We're expanding sizing as we grow, because genuine inclusivity means everyone gets options.  joni leakproof period underwear provides secure, full coverage. If you're used to a looser fit or are between sizes, we recommend sizing up.

The Bottom Line: Period Underwear Is a Choice, Not a Moral Imperative

Here's what we're not going to do: tell you that reusable period underwear is morally superior. 

People who menstruate have the right to choose period products that work for their body, life, and circumstances. Sometimes that's reusables. Sometimes it's disposables. Sometimes it's a mix.

We've donated over a million joni products to communities in need since 2020—and most of those were disposables. Because accessibility means meeting people where they are. Because a sustainable pad in someone's hands is better than aspirational reusables sitting on a shelf.

joni period underwear is here for people who've been waiting for a reusable that doesn't ask them to compromise on safety, comfort, or values.

If that's you—welcome. We're so glad you're here.

If that's not you right now? That's okay too. We'll be here when you're ready. And in the meantime, we're focused on making all period care—disposable and reusable—more sustainable, accessible, and equitable.

Because period care is a human right. And everyone deserves options.