By: Carrie Yotter
Published On: 10/20/26
SAY HELLO TO UNDERDAYS:
Underwear That Makes Every Version of Perfect Possible
Summary
•What years of research taught Underdays about women and their underwear.
•Why the smallest design details became some of the brand’s biggest priorities.
•How Underdays is making the case for underwear as self-care.
•Why the smallest design details became some of the brand’s biggest priorities.
•How Underdays is making the case for underwear as self-care.
Our exclusive interview with co-founders Amelie Salas and Oria Mackenzie.
What can underwear do for you?
It’s a question the co-founders of cult intimates brand Underdays realized no one was really asking. Maybe because we weren’t expecting enough from our underwear in the first place.
Comfort or aesthetics. Function or feeling good in what you’re wearing. For years, those seemed to be the choices—and choosing both was surprisingly hard to come by. Amelie Salessy and Oria Mackenzie thought underwear could do better.
A few of our FP teammates swear by Underdays—as in, there is really no other option. And once you start thinking about underwear as a form of self-care, you start wondering what else that first layer might be capable of.
So we asked Amelie and Oria about the thinking behind Underdays, the details we’ve been overlooking, and what exactly makes underwear “good for you.”
It’s a question the co-founders of cult intimates brand Underdays realized no one was really asking. Maybe because we weren’t expecting enough from our underwear in the first place.
Comfort or aesthetics. Function or feeling good in what you’re wearing. For years, those seemed to be the choices—and choosing both was surprisingly hard to come by. Amelie Salessy and Oria Mackenzie thought underwear could do better.
A few of our FP teammates swear by Underdays—as in, there is really no other option. And once you start thinking about underwear as a form of self-care, you start wondering what else that first layer might be capable of.
So we asked Amelie and Oria about the thinking behind Underdays, the details we’ve been overlooking, and what exactly makes underwear “good for you.”
FREE PEOPLE: You both came to Underdays from Farfetch. Was there anything you had to "unlearn" about fashion before building a brand of your own?
UNDERDAYS: Coming from big fashion houses and companies like Farfetch and Burberry, you're surrounded by resources (big budgets, established teams, a brand that already has gravity). Building from scratch meant we had to unlearn all of that very quickly. We learned to do a lot with a little, and honestly that constraint makes you sharper.
The other big one was seasons. The fashion calendar runs on Autumn/Winter and Spring/Summer collections, which the whole industry follows. Underwear doesn't. It's an always-on product, which means we have to create our own moments of excitement throughout the year rather than riding the wave everyone else is on. That's been one of the more creative challenges, figuring out how to keep the brand feeling alive and relevant in January as much as September.
FP: You performed extensive research—not least of which interviewing women and scouring Reddit threads—in search of the "perfect" underwear. What's something you've learned that genuinely surprised you? And does the perfect underwear exist?
U: The most surprising thing we learned was how women have been conditioned to accept discomfort as normal. We'd hear the same thing again and again in our interviews: "it's just underwear, you get used to it." That sentence became something of a north star for us, because getting used to it is not the same as being good. When customers started writing to tell us they "forgot they were wearing it," that wasn't a small compliment. For a lot of them, it was a genuinely new physical experience, and that tells you exactly where the bar had been set before us.
The other thing that stopped us in our tracks was the gusset. It sounds unglamorous, but gusset length and placement is probably the single most underappreciated detail in underwear, one of the most common sources of irritation and discomfort.
As for perfect underwear: we think "perfect" is plural. The perfect pair for a long-haul flight is not the perfect pair for a workout is not the perfect pair for a satin-slip dress. What we can offer is the underwear that makes every version of perfect possible.
UNDERDAYS: Coming from big fashion houses and companies like Farfetch and Burberry, you're surrounded by resources (big budgets, established teams, a brand that already has gravity). Building from scratch meant we had to unlearn all of that very quickly. We learned to do a lot with a little, and honestly that constraint makes you sharper.
The other big one was seasons. The fashion calendar runs on Autumn/Winter and Spring/Summer collections, which the whole industry follows. Underwear doesn't. It's an always-on product, which means we have to create our own moments of excitement throughout the year rather than riding the wave everyone else is on. That's been one of the more creative challenges, figuring out how to keep the brand feeling alive and relevant in January as much as September.
FP: You performed extensive research—not least of which interviewing women and scouring Reddit threads—in search of the "perfect" underwear. What's something you've learned that genuinely surprised you? And does the perfect underwear exist?
U: The most surprising thing we learned was how women have been conditioned to accept discomfort as normal. We'd hear the same thing again and again in our interviews: "it's just underwear, you get used to it." That sentence became something of a north star for us, because getting used to it is not the same as being good. When customers started writing to tell us they "forgot they were wearing it," that wasn't a small compliment. For a lot of them, it was a genuinely new physical experience, and that tells you exactly where the bar had been set before us.
The other thing that stopped us in our tracks was the gusset. It sounds unglamorous, but gusset length and placement is probably the single most underappreciated detail in underwear, one of the most common sources of irritation and discomfort.
As for perfect underwear: we think "perfect" is plural. The perfect pair for a long-haul flight is not the perfect pair for a workout is not the perfect pair for a satin-slip dress. What we can offer is the underwear that makes every version of perfect possible.
WHAT UNDERDAYS DOES
FP: Your collection aims to "solve" many issues shared by women. What does Underdays offer that you felt was genuinely missing from the category?
U: The question nobody was asking: what can underwear actually do for you? The category had been frozen in a false choice for decades, with women having to choose between dull-but-comfortable basics on one side, pretty-but-uncomfortable lingerie on the other. Both sides have been dominated by synthetic materials, male-led design and positioning built around the male gaze rather than the wearer's experience.
What was missing was the same thing that had transformed beauty, activewear, personal care: the intersection of health, function and aesthetics, without compromise.
U: The question nobody was asking: what can underwear actually do for you? The category had been frozen in a false choice for decades, with women having to choose between dull-but-comfortable basics on one side, pretty-but-uncomfortable lingerie on the other. Both sides have been dominated by synthetic materials, male-led design and positioning built around the male gaze rather than the wearer's experience.
What was missing was the same thing that had transformed beauty, activewear, personal care: the intersection of health, function and aesthetics, without compromise.
Women have started reading ingredient labels on their serums, asking whether their protein powder was hormone-disrupting, choosing activewear by its moisture-wicking credentials. And then they'd pull on a pair of synthetic underwear against the body's most intimate skin for twelve hours and not ask a single question. We wanted to close that gap. Breathable, OEKO-TEX certified fabrics. A gusset designed with the same seriousness we give to every other construction detail. Technology like UNDERskin™, a pre- and probiotics treatment infused into the fabric, that actively supports intimate health rather than being neutral at best and harmful at worst. And all of that in something you actually want to wear. Some are calling it "carewear"--we just call it what underwear should have always been.
FP: I love "underwear as self-care." What does that mean to you—and how do innovations like UNDERskin™ and HeiQ Skin Care™ help make something we wear every day do more work?
U: There's a phrase gaining traction around what we do, "carewear", the idea that skincare didn't stay in the bathroom. And that feels exactly right to us. For us, self-care is not a Sunday ritual that requires a block of time and a cabinet full of products, it's the decision to choose something that works for your body every day.
With UNDERskin™, our Everyday collection is finished with HeiQ Skin Care™, a synbiotic treatment that delivers both prebiotics and probiotics directly into the fabric. It's activated by body heat and movement, so as you wear it, it's quietly supporting your skin's natural microbiome all day. It's 100% biobased, clinically tested, and lasts up to 40 washes. You feel nothing different. The fabric feels exactly the same. It just works, which is the whole point. It’s an added benefit to something you're already doing every day: putting on your underwear.
FP: What does your "getting dressed" ritual look like?
U: Making underwear for a living means we probably think about this more than most. We know firsthand how much that first layer can affect your entire day; the wrong pair and you're adjusting, uncomfortable, distracted before you've even left the house. We like to say it's your first intentional choice of the day, and we genuinely believe that. It sets the tone for everything you put on after and how you feel as you get on with your day.
FP: I love "underwear as self-care." What does that mean to you—and how do innovations like UNDERskin™ and HeiQ Skin Care™ help make something we wear every day do more work?
U: There's a phrase gaining traction around what we do, "carewear", the idea that skincare didn't stay in the bathroom. And that feels exactly right to us. For us, self-care is not a Sunday ritual that requires a block of time and a cabinet full of products, it's the decision to choose something that works for your body every day.
With UNDERskin™, our Everyday collection is finished with HeiQ Skin Care™, a synbiotic treatment that delivers both prebiotics and probiotics directly into the fabric. It's activated by body heat and movement, so as you wear it, it's quietly supporting your skin's natural microbiome all day. It's 100% biobased, clinically tested, and lasts up to 40 washes. You feel nothing different. The fabric feels exactly the same. It just works, which is the whole point. It’s an added benefit to something you're already doing every day: putting on your underwear.
FP: What does your "getting dressed" ritual look like?
U: Making underwear for a living means we probably think about this more than most. We know firsthand how much that first layer can affect your entire day; the wrong pair and you're adjusting, uncomfortable, distracted before you've even left the house. We like to say it's your first intentional choice of the day, and we genuinely believe that. It sets the tone for everything you put on after and how you feel as you get on with your day.
WHAT YOUR UNDERWEAR SAYS ABOUT YOU
FP: What can someone's underwear drawer tell you about them?
U: It tells you exactly where she is with compromise. The $10 multipack that's been in there for years says she's been putting herself last. The beautiful set she never reaches for says she's accepted that comfort is the price of looking good. What we are really trying to do with Underdays is meet women at the moment they're done with that trade-off, and that moment is different for everyone. For some it comes early, for others it takes longer. But there's always a point where you think, actually, why am I still settling? That's who we're here for. Someone who's ready to stop choosing between comfort, style and function, because she shouldn't have to pick.
U: It tells you exactly where she is with compromise. The $10 multipack that's been in there for years says she's been putting herself last. The beautiful set she never reaches for says she's accepted that comfort is the price of looking good. What we are really trying to do with Underdays is meet women at the moment they're done with that trade-off, and that moment is different for everyone. For some it comes early, for others it takes longer. But there's always a point where you think, actually, why am I still settling? That's who we're here for. Someone who's ready to stop choosing between comfort, style and function, because she shouldn't have to pick.
FP: What pair do you most reach for, and why?
U: We can't pick just one. Honestly, the Everyday Collection as a whole is what we both live in. The Everyday Thong is the non-negotiable style for back-to-back days, no VPL, any day where you just need to forget you're wearing something. And when we want a little more coverage, the Everyday Cheeky is right there. Same ultra-soft TENCEL™ Micromodal, same crossover waistband, same UNDERskin™ technology working away in the background. We went through over fifty rounds of testing to get this collection right, and we're both still reaching for it every single morning. That feels like the most honest answer we can give.
U: We can't pick just one. Honestly, the Everyday Collection as a whole is what we both live in. The Everyday Thong is the non-negotiable style for back-to-back days, no VPL, any day where you just need to forget you're wearing something. And when we want a little more coverage, the Everyday Cheeky is right there. Same ultra-soft TENCEL™ Micromodal, same crossover waistband, same UNDERskin™ technology working away in the background. We went through over fifty rounds of testing to get this collection right, and we're both still reaching for it every single morning. That feels like the most honest answer we can give.
OVER THE MOON FOR UNDERDAYS
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