Underwear That Stops Fighting You Back.
No digging waistbands. No riding-up briefs. No sweaty-by-noon syndrome. Just soft, breathable bamboo viscose underwear built to disappear, from thongs to bras to anti-chafe body shorts.
You Know The Feeling.
Somewhere between getting dressed and 3pm, your underwear starts working against you.
The Midday Dig
Waistbands that cut in and leave a red ring by lunchtime. Every single day.
The Cotton Clam-Up
Fabric that goes damp, clingy, and just sits there instead of breathing with you.
The Thigh Rub
Chafing under dresses, skirts, and looser shorts that ruins an otherwise great outfit.
The Bra Betrayal
Underwire and straps that dig in the second you sit down for more than an hour.
None of that means you're "too sensitive." It means the fabric is wrong. Here's what we build with instead.
Cotton vs. Bamboo Viscose: What Your Underwear Is Actually Made Of
Most brands would rather you didn't ask. We'll show you the comparison.
Regular Cotton
- Traps heat and moisture against your skin
- Gets stiff and scratchy after a few washes
- Can irritate sensitive skin
- Conventional cotton farming is water- and pesticide-intensive
Step One Bamboo Viscose
- About 2x more breathable than cotton, pulling moisture away from skin
- Stays soft and silky, wash after wash
- Naturally hypoallergenic, gentle on sensitive skin
- Made from organically grown bamboo that needs far less water than cotton
Meet SmoothFit
Our signature seamless fabric blend, used across the thong, bikini brief, full brief, boyleg, and padded bra. Four-way stretch, second-skin fit, and zero rough seams or tags that dig in.
Ratings reflect Step One's global customer base across Australia, the UK, and the US. If you want a second opinion beyond ours, that's exactly what Trustpilot is for.
The Bottom You'll Actually Live In
Built for the days a regular pair can't handle: under skirts, dresses, loose shorts, or just a long day on your feet.
- UltraGlyde™ anti-chafe inner-thigh panels: smooth, low-friction fabric exactly where regular seams rub.
- Seamless SmoothFit build that disappears under fitted or floaty fabric alike.
- Bamboo viscose breathability so a longer style never feels heavy or sweaty.
Comfort That Blooms, Not Digs
No underwire jabbing your ribs. No straps cutting in by 2pm. The SmoothFit Wireless Padded Bra is soft, seamless support built from the same bamboo viscose blend as the rest of the range, so what's holding you up feels as good as what's not.
- Wireless, seamless SmoothFit construction
- Breathable bamboo viscose, hypoallergenic against sensitive skin
- Wide, soft-set straps designed not to dig in
Find Your New Everyday
Every style below is built from the same bamboo viscose fabric science. Pick your coverage, not your compromise.
Bundle & Save
Mix sizes, colors, and styles across a 5- or 10-pack and save up to 34% off.
Try Them. Love Them. Or They're Free.
We're confident enough in the fabric to put our money where our mouth is.
First Pair Guarantee
Full refund on your first opened and worn pair if you don't love it, for any reason.
How the guarantee worksFree US Shipping
Free shipping on every order in the US. No minimum spend required.
Easy Returns
Picked the wrong size? Unopened items are easy to exchange or return.
Returns & exchangesFrequently Asked Questions
What's actually different about bamboo viscose underwear?
Bamboo viscose is roughly twice as breathable as cotton, pulling moisture away from your skin instead of trapping it. It's also naturally hypoallergenic, so it's gentler on sensitive skin, and it stays soft wash after wash instead of going stiff. Our bamboo is organically grown.
What is SmoothFit fabric made from?
SmoothFit is our seamless fabric blend: 79% bamboo viscose, 15% polyamide, and 6% spandex. It's used across the SmoothFit Thong, Bikini Brief, Full Brief, Boyleg, and Wireless Padded Bra for a four-way-stretch, second-skin fit with no digging seams or tags.
Will the Body Shorts actually stop my thighs from chafing?
The Women's Body Shorts are built specifically for this problem, with UltraGlyde™ anti-chafe inner-thigh panels and a seamless construction designed to reduce friction under skirts, dresses, and looser bottoms. They're our top recommendation if inner-thigh chafing is your main frustration. Fit and results can vary person to person, but this is the style engineered for exactly that.
What if my first pair doesn't fit or I don't love it?
You're covered by our First Pair Guarantee: if you don't love your first opened and worn pair for any reason, we'll give you a full refund. Unopened items from multi-item orders can also be exchanged or returned.
Is shipping really free, with no minimum?
Yes, every US order ships free, with no minimum spend required.
How much can I save by bundling multiple pairs?
You can mix and match sizes, colors, and styles across a 5- or 10-pack and save up to 34% off compared to buying single pairs. Exact bundle pricing is shown at checkout on each product page.