MODEL_INFO=Model wears Size S

The Everyday Thong

£18

Core :

Limited Edition :

Size :

Size guide

XS S M L XL XXL

Product fit

1
2
-15%
4
-20%

Low on stock. Get it while you can!

Sorry, this item is out of stock

Item is out of stock. Preorder now for shipping on

Estimated shipping on

1

Preorder item

This item is currently available for preorder only.

Delivery estimate is

Free UK Delivery over £60+
Free UK Returns & Exchanges

Our Everyday Thong in [Black/ Lilac/ Sand/ Butter/ Taupe], now with HeiQ Skin Care™ technology. A clinically tested synbiotic treatment infused in the fabric that helps restore your skin's natural balance, promote a healthier skin appearance, and strengthen your skin's protective barrier. No extra steps. Just wear it.

The Everyday Thong is a mid-rise thong designed for invisible, all-day comfort. The ultra-soft modal fabric and flat leg elastics mean zero visible panty lines under any outfit, including tight-fitting dresses, leggings, and light fabrics. The wider waistband sits securely without cutting in, and the longer gusset provides extra protection.

• UNDERskin™: 100% biobased synbiotic technology, supports your skin's natural microbiome, lasts up to 40 washes. Data provided by HeiQ based on testing conducted on other materials.

• Style: Mid-rise thong, minimal coverage


• Rise: Mid-rise but can be adjusted to your preference


• Coverage: Minimal back coverage


• VPL (Visible Panty Lines): None — this is Underdays’ best option for zero VPL


• Best For: Daily wear, under tight clothing, dresses, leggings, light fabrics

•Fabric: 92% TENCEL™ Micromodal, 8% Elastane

• UNDERskin™: Prebiotics + probiotics infused in the fabric transfer to your skin on contact, supporting a balanced, healthy-looking microbiome. 100% biobased. Powered by HeiQ Skin Care™.

•Sustainability: Our underwear is made from TENCEL™
Modal, sustainably derived from trees and twice as soft as cotton. Gentle on the skin and made to feel like nothing at all.

•OEKO-TEX certified: All of the fabrics we use are independently certified by OEKO-TEX (SH015 210990 Testex), meaning all our underwear is free from harmful substances.

•Waistband: Wide, soft self-fabric, no-dig, no-roll

•Gusset: Extra-long

•Leg Elastic: Flat comfortable elastic for no VPL

•Care: To preserve the HeiQ Skin Care™ treatment, wash at 30°C on a gentle cycle. The synbiotic technology is designed to last up to 40 home washes. Data provided by HeiQ based on testing conducted on other materials.

We also recommend to wash your Underdays in a mesh laundry bag. Air-dry flat in a shaded area. Do not bleach. Do not iron or tumble dry.

  • We offer both Next Day Delivery and Standard Delivery

Size down for a snugger fit, size up for a more relaxed fit.
Exchanges available if the size isn’t right.

View size guide
Select size
size chart

your underwear deserves better

You care about your skin, your wellness, your rituals. We’re pioneering care for your most intimate parts.

Powered by UNDERskin™

Prebiotics and probiotics, infused into the fabric, transferring to your skin all day. Supports your microbiome. Strengthens your skin barrier. Promotes a healthier appearance. 100% biobased. Developed in Switzerland.

Twice the softness of cotton

Our underwear is made from TENCEL™ Modal—sustainably derived from trees and twice as soft as cotton. Gentle on the skin and made to feel like nothing at all.

Let your ____ breathe freely

TENCEL™ fibers are unfavorable for bacteria growth. They wick away moisture and keep you fresh through the day. Designed to help reduce the risk of unwanted infections.

OEKO-TEX Certified

OEKO-TEX® certified —clean, non-toxic with no harmful substances

set apart by design

TENCEL™  modal antimicrobial fabric derived from trees

Prebiotics + probiotics infused in the fabric for a healthier skin microbiome

Tested by real women, with over 1,000 five-star reviews

Engineered for optimal airflow and breathability

A 2cm extra-long gusset for everyday protection

Soft leg elastics designed to eliminate digging in

underwear that cares for your skin

frequently asked questions

The Everyday Thong is made from ultra-soft modal for daily comfort — ideal under work clothes, jeans, and dresses. The Workout Thong uses a moisture-wicking performance fabric that handles sweat and movement during exercise. Same flattering thong shape, different fabric engineered for different purposes.

Yes. The Everyday Thong is Underdays’ best option for completely invisible underwear under any outfit, including white, thin, or body-hugging fabrics.

Yes — that’s exactly what it’s designed for. The modal fabric is softer than cotton and the wider waistband sits flat without cutting in. Many of our customers wear the Everyday Thong as their daily go-to, not just for special occasions or specific outfits.

Our Everyday Collection is treated with HeiQ Skin Care™ — Swiss synbiotic technology that supports your skin's microbiome through fabric-to-skin contact. Underwear that works like skincare. It's a cosmetic treatment that promotes promotes healthy skin appearance, not a medical product, it doesn't diagnose, treat, or prevent disease.

No, it's already built in. HeiQ Skin Care™ is embedded directly into the fabric during production, so it's working from the very first wear. No creams, sprays, or steps required.

No change to handfeel, breathability, colour, or fit, it feels exactly like the Everyday you already love. Non-irritant, human skin patch tested, and all ingredients INCI-listed.

For light activities like walking, gentle yoga, or Pilates, the Everyday Thong works well. For anything higher intensity — running, HIIT, hot yoga, weight training — the Workout Thong’s moisture-wicking fabric will keep you drier and more comfortable.

We’re focused on making the best underwear possible. Bralettes are currently in development— sign up to our mailing list to be the first to know when they launch.

Our core colours such as Black and Sand are always available and restocked regularly. Fashion colours and seasonal drops are limited edition — once they sell out, they won't be coming back. If you spot a colour you love, we'd recommend grabbing it before it's gone. Follow us on social or sign up to our mailing list to be the first to know when new color drops land.

product details