How do iteration undergarments fit?

Comfortable Supportive Wirefree Bras With Top Notch Design Features: Our undergarments are crafted from luxurious TENCEL™ Modal fabric, designed to fit and feel like a second skin without the use of pokey wires or stiff, unforgiving pads. This ensures they are dreamy and perfect for everyday wear, letting you focus on your day without noticing you're wearing anything. There are also lightweight supportive layers hidden inside to help lift and shape your tissue towards the center front of your body without creating the dreaded uniboob.

Check out our fit guide to find your perfect match! To find your ideal fit, refer to our size charts. For a snugger, more supportive fit, choose the nearest size down. For a looser, more relaxed fit, select the size that matches your measurements. If you're between sizes, we recommend sizing down due to our super stretchy fabric and extra adjustment rows, designed to extend the garment's life and adaptability.

What sizes do you carry?

Standard Cup Bra Sizes: Our standard bra cup range runs from XS through 3X. This cup size range is best suited for women who typically wear between A and D cup bras. This Standard Cup size range is available for exploration here.

Fuller Cup Bra Sizes: Our fuller bra cup range runs from XS+ through 3X+, with the + size indicating the fuller cup. Fuller cup sizes offer a slightly smaller band so they’re more supportive to a fuller bust with a larger cup to accommodate more volume. If you typically opt for DD cup sizes or larger, you will probably want to try sizing into a Fuller Cup size. Journey into our Fuller Cup size range by checking out the size range here.

Underwear Sizes: We offer sizes XS through 3X for underwear. Check out our underwear size chart for more detailed information.

Community Input: If your size isn't currently available, we'd love to hear from you! Email us at, and we'll consider your feedback for our future planning.

How do I know what size underwear to get?

Using the Size Chart: Consult our underwear fit guide to determine your best fit. Think about how you prefer your undies to fit:

For a snugger fit that minimizes garment shifting, opt for the nearest size down.

For a roomier, more relaxed fit, choose the size that matches your measurements.

As most people can wear multiple sizes in our products given the nature of the fabric and elastics, this approach should ensure you get the comfort and support tailored to your individual needs and preferences!

Where can I find your size charts?

Click here to access our bra size charts.

Click here to access our underwear fit guide + size chart.

Got a fit question that you need answered? Don’t hesitate to email our team at and we’ll help you get the right size.

How do I know my bra fits?

Band Fit: The band should be snug around your body and level all the way around, not riding up in the back. It should be supportive but not leave lasting red marks.

Cup Fit: The cups should fully contain your breasts without overflow or gapping. For non-wired bras, ensure each breast stays on its own side without creating a uniboob. For wired bras, the center gore should lie flat against your sternum.

Strap Fit: The straps should stay in place without digging into your shoulders or slipping off.

When all these criteria are met and the bra is comfortable throughout the day, you've found a good fit!

If I’m between two sizes, which one should I pick?

If you’re between two sizes and you aren’t sure which to pick, it’s best to understand how you like your undergarments to fit. 

If you’d prefer a snugger, more supportive fit, we suggest you pick the smaller size you fall into in our size charts. Keep in mind that our bras come with 4 rows of adjustability, so if you opt for a snug fit, your bra will loosen over time and become a little more comfortable while allowing you to adjust it to be smaller and more supportive as time goes on. 

If you’d prefer a looser, more comfortable fit, we suggest you select the larger size. Opting for a more comfortable fit from the start might mean that you have less support as time goes on since your adjustments levels will fit looser from the beginning.

What are the most common fit issues + solutions?


Band Rides Up at Back

Issue: A band that rides up the back means it’s too big or has stretched out over time.

Solution: The band should fit snugly on the loosest hook when new. Try sizing down in the band but up in the cup (for example, from 36C to 34D) to maintain the cup volume while getting a tighter fit around the body.

Band Causing Longterm Indents + Redness

Issue: If your bra band is too tight, it can leave red marks and indents on your skin that linger long after you take it off.

Solution: A bra band should feel snug but not restrictive. If it’s leaving marks, consider sizing up in the band. The band is the foundation of support, so it should feel comfortable and secure, not like it's squeezing too tightly. Remember, your bra is there to support you gently throughout the day.


Cups Gape or Wrinkle

Issue: If the cups of your bra gap or wrinkle, it usually means they're too big.

Solution: Opt for a smaller cup size. Ensure that the bra cup contours to your breast without any space between the fabric and your skin, like a gentle hug that feels just right.

Cups Overflow or Create Muffin or Quad Boob

Issue: If your breasts spill out of the top, sides, or bottom of the cup, the cups are too small.

Solution: Try a larger cup size to ensure all your breast tissue is comfortably encased within the cups, providing a secure and flattering fit.

Underwire Digging Into Tissue

Issue: When the underwire sits on or digs into your breast tissue, it often indicates that the cups are too small.

Solution: Switch to a larger cup size to give yourself more room. The underwire should sit comfortably under your breasts, encircling them with support, not pinching or poking.


Straps Slip Off Shoulders

Issue: Straps that slip off your shoulders can be frustrating and indicate that they’re too loose or the bra is not the right shape or fit.

Solution: Tighten the straps to find a snug but comfortable fit. If they still slip, consider a different bra style with closer-set straps or a racerback design that stays put.

Straps Digging Into Shoulders

Issue: If your bra straps are digging into your shoulders, this can often mean that the band isn’t providing enough support, putting too much pressure on the straps causing long-term indents in the shoulder area.

Solution: Ensure your band fits correctly first—it should be tight enough to stay in place but comfortable enough not to dig in. Once the band is set, adjust your straps so they’re snug without being tight. The straps should contribute to support, not bear all the weight. Consider a bra with wider straps for better weight distribution and enhanced comfort.


FABRICS: All our products currently use a dreamy soft TENCEL™ Modal spandex blend as our base material, so you get the benefits of this incredible fiber right against your skin. 

  • Bras: Our bras also contain an extra fabric mesh hidden inside the cups currently made of 87% nylon and 13% elastane. Our goal is to move to either 1.) bio-based nylon or 2.) recycled nylon quality in a future production order as soon as possible. Right now, this material is necessary to provide the supportive shaping and lift that our bras offer and better longevity than modal alone. 
  • Underwear: For our underwear we’ve specifically avoided using elastics to make the dreamiest and comfiest underwear you’ve ever tried on. The only elastics are used in the threads which make for an ultra comfortable fit. 

ELASTICS: For elastics in our bras, we use a specialty elastomeric yarn that is fully recyclable. Unlike typical elastic yarns, the name is X4J and we’re pretty proud of it. This material has moisture wicking and cooling properties to allow you to stay comfortable all day long. The best feature of our elastics, though, is the enhanced stretch capabilities it offers that allows for 28% to 64% less force than spandex. This creates a more flexible fit that meets you where you are, offering enhanced comfort that feels like a second skin. 

HOOK + EYES: Our hook + eye is made with a nylon spandex fabric material as well as a 2mm plush foam to allow for a comfortable fit on your back with no digging. Our goal is to move to a 1.) Bio-based nylon or 2.) Recycled nylon fabric covering as soon as minimums will allow. Currently this has been out of reach due to the material commitment required for ordering as a small business. 

HARDWARE: All hardware including our sliders, rings, and convertible back j-hooks on our bras are created with a zinc alloy. This is a recyclable material that is rust and corrosion resistant and very light, strong, and durable.


At Iteration, quality is woven into every layer of our design, development, and production processes. It begins with selecting premium, natural materials that are both durable and gentle on the skin. We use higher than average stitches per inch (SPI) to ensure that the garments are made to be ultra durable and long lasting. Not only that, but our design team’s extensive experience in the underwear industry has given us unique and unparalleled insight to making garments that are incredibly high quality by leveraging the best materials available as well as new construction techniques.

Beyond the development process, during the sample stages, our designs undergo rigorous wear and wash testing by our team and community to ensure comfort, functionality, and durability. We organize repeated and extended wash and wear tests to make sure products hold up and the fabrics don’t look ragged or pilly. By integrating feedback directly into the design process, we continually refine each product's fit, feel, and durability. Additionally, we partner with factories that not only meet but exceed industry standards for ethical and sustainable practices, ensuring that every worker involved in making our products is treated with respect and fairness.


Ensure your iteration intimates last as long as posible and stay as fresh and inspiring as the day they were created. To maintain the beauty and integrity of your undergarments, we suggest the below care techniques. Kind reminder to launder your bras after 2 or 3 wears and make sure to give them a day or two to rest between wearing. For undies, we suggest washing after every wear (hopefully, that goes without saying😉). 

1. Cold + Gentle Cleansing: Begin with a mild detergent and wash in cold water to preserve the fabric's natural qualities and colors. Wash away the remnants of the day and prepare your garment for its next use.

2. Color Companions: Wash your intimates with like colors. This extra step prevents the colors from straying too far off course, ensuring they remain vibrant and true throughout many wears.

3. The Art of Drying: Whenever possible, line dry your garments. Let them bask in the breeze and dry naturally. This not only conserves energy but helps maintain the fabric’s structure and softness. If you must use a dryer, opt for a gentle tumble on low heat.

4. No Harsh Elements: Steer clear of bleach and other harsh chemicals. that strip away color and weaken fibers. If you’ve got a stain you want lifted, opt for a non-bleach alternative like OxiClean.

By following these care instructions when possible, you ensure your iteration undergarments will be clean and last longer. .


We're thrilled you're excited about our color journey! 🌈

While our debut collection has set the stage, we're eager to splash more hues into your wardrobe. To influence our next color adventure, join The Co-Lab, where your voice helps us decide whether to deepen our neutrals or introduce bold, limited edition pops of color. In the meantime you can learn more about the current color offering and our inspiration behind them on our Color Palette Page.

And don't miss out—sign up for our email newsletter to be the first to know about our upcoming color releases and stay in the loop with every vibrant update! 💜


Our design process is always a continuous conversation with our fabulous co-creation community. We're dedicated to evolving our range to include more styles and sizes that resonate with your needs and desires.

Become a part of The Co-Lab to have a direct hand in shaping our future offerings.

Don't forget to subscribe to our email newsletter to gain early access to all the new styles, sizes, and colors we're bringing to life.

Let's create something extraordinary together!


Got a product or fit question that you need answered? Don’t hesitate to email our team at and we’ll help you get the right size.

Community + Co-Creation


Co-creation at iteration means YOU have a voice creating the bras and undies YOU want. Co-creation is our manifesto in action. It’s a dynamic community-led collaboration where your ideas meet our design expertise to craft intimates that resonate deeply with your needs and values. We believe that the best designs arise from diverse perspectives coming together, leading to products that are not only loved, but lived in. By joining together, we continuously elevate the quality and relevance of each piece, ensuring that our co-created bras and undies are truly next level.

Become a part of The Co-Lab to have a direct hand in shaping our future offerings.


Join our community to be a part of something bigger than just fashion. Have a real say in product creation. At iteration, YOUR voice is celebrated and YOUR ideas spark possibilities. The best products emerge from collective insight, so come co-create with us to and be part of the solution to create better bras and undies - ones that solve YOUR problems! At iteration, we value each voice and believe that the best ideas emerge from collective insight. Here, you’re not just a member, but a co-creator whose experiences and opinions shape everything we do. Together, we can redefine the way intimates are made, worn, and loved.


If you want to be part of creating better undergarments for women, by women - consider joining our community. If you’ve struggled to find good bras and undies that fit - then you’re in the right place. If you believe in making a positive impact through fashion - you can make a real difference here. If you like sharing ideas, collaborating, and being part of “something bigger” - you are a great fit for our community. Whether you're passionate about sustainability, eager to share your creative ideas, or simply want intimates that feel as good as they look, your perspective is invaluable. Our co-creation community thrives on diversity—of thought, background, and possibilities. Come as you are, bring your unique insights, and let's innovate together!


Joining is simple and impactful Click Here to go to our Co-Lab Facebook group. There’s a big purple button in the upper right hand corner that says “Join Group.” Add a few details, agree to our rules, and we’ll get you situated inside. Whether you’re curious about co-creation and just want to see or if you have a ton of ideas to share, your participation and insights are crucial. Sign up today and start making a difference in what we create together tomorrow.


While much of the co-creation and collaboration occurs in the Co-Lab on Facebook, we share alot of updates and surveys in our monthly newsletters and emails so you can follow along. Make sure that you are signed up to receive those here on the bottom right of the page. Additionally, if you have ideas to share or want to check-in to see what we’re working on, feel free to email us at


Beyond the joy of seeing your ideas and opinions come to life in our collections, joining the Iteration community offers a host of enriching experiences and perks. You'll gain exclusive access to exclusive wear-testing opportunities with the chance to provide direct feedback that shape or final garments. Enjoy special invitations to town-hall meetings, discount codes, participate in polls, and enter competitions. Plus, you’ll meet like-minded individuals who share your passion for thoughtful, ethically made fashion. By joining us, you contribute to a sustainable future and ensure that the clothes we wear are not just made, but made thoughtfully and with purpose. Click here to explore becoming part of The Co-Lab


What does sustainability mean at iteration?

At iteration, sustainability is central to everything we do.

We've embraced a slow and deliberate development process, focusing on creating long-lasting, high-quality products through community co-creation, innovative design, and natural, eco-friendly materials. Our commitment extends to ethical practices with their suppliers, ensuring fair treatment and wages for workers. Our five main sustainability pillars are community co-creation, natural materials, smart design, durability, and ethical practices. We also prioritize transparency and continuously involve our co-creator community in our sustainability efforts and improvements.


iteration products are made with love in the beautiful country of Sri Lanka. We chose our factory for its attention to detail, product quality, and the exceptional care and regard it shows employees. Our factory prides itself on treating employees fairly, paying above the local minimum wage, and ensuring employees receive a regular paycheck–even if orders get canceled, or lines get shut down (like during COVID, when many other local factories laid off workers without pay). This factory is bright, clean, well-organized, and safe. Workers are provided training, transportation, meals and tea, regular breaks, and reasonable working hours with limited overtime.


We’ve searched far and wide for the very best materials for iteration bras + undies, while also limiting our footprint by selecting local options within the supply chain whenever possible.

Fabrics and hardware are sourced from China. Elastics, hook and eyes, cotton gusset lining and heat seals come from the local supply chain in Sri Lanka. Each item was hand-selected for its unique properties and characteristics to make the highest quality intimates.


Modal is a cellulosic fiber created from beech trees! Beech wood forests are a natural and renewable raw material source that grows quickly and can be replenished easily. Modal fibers are biodegradable and compostable (unlike synthetic fossil-fuel derived nylons and polyesters), and modal production requires less water (unlike natural cotton, which requires large H2O volumes).

Modal fabric is super soft – think 2x as soft as cotton – and it has a cooling touch. Our fabric is some of the softest and coziest material we've crossed paths with – and we've journeyed down A LOT of paths to find the best fabric possible. Modal supports body temperature regulation, exhibits excellent fabric breathability, and has efficient moisture management to keep you cool and dry. 

All these properties combine to create an environment less favorable for bacterial growth, so modal is a preferred hygienic choice for intimates. Even more impressive is that modal is more durable than cotton and can withstand repeated wash and dry cycles better without pilling. It holds its shape well and is resistant to shrinkage. What's not to love!?!

Our modal fibers are made by Lenzing, one of the best modal fiber producers in the world because of its sustainable sourcing and production practices. Lenzing modal has a sixfold lower environmental impact than regular modal. All wood comes from FSC-certified, responsibly managed forests, and Lenzing's modal fibers are produced in a closed-loop process. It's time to woo, woo-girls. 


We believe all participants in producing iteration products must be treated fairly and ethically. That's why we selected a partner who provides employees livable wages and safe working conditions and is committed to transparency and responsible supply chain practices. 

Our factory is in the process of getting its SEDEX certification.

What's that? Achieving SEDEX certification proves that a company has undergone a rigorous ethical and social compliance audit to ensure it operates responsibly. While the accreditation is yet to be completed by our factory, we love the idea of putting our money where our mouth is by supporting a smaller, local manufacturer who is making the commitment (and investment of time and resources) to obtain SEDEX certification.

Additionally, we have thoughtfully structured our supply chain to include sourcing partners who follow the highest environmental standards. Some of these include:

OEKO-Tex Standard 100: This is a label for textiles that have passed safety tests for the presence of harmful substances. Our modal fiber producer (Lenzing), the yarn spinner, the fabric dyer, the hardware producer, and the elastics supplier all have this certification for the materials in our supply chain.

ZDHC: This is the leader in the fashion industry for its Roadmap to Zero program to eliminate harmful chemicals from the global supply chain. The dyes for our cotton gusset linings come from Japan and are ZDHC certified - because chemicals anywhere near your eh-hmmm (whatever you like to call it), are gross.


The team at iteration is committed to plastic-free packaging. We use paper-based mailers made from 100% recycled content (nearly all of which comes from post-consumer waste diverted from landfills). All our tissue paper is made from 100% recycled content. Instead of plastic poly bags, we've selected paper-based packaging from FSC-certified forests to hold the garments and ensure they are protected on their way to you. All packaging materials are recyclable!


Hopefully, that won't happen for a while since we built everything from the ground up with longevity in mind! 😉 

We used higher stitch counts to create more durable garment construction. We selected a dreamy fabric that resists pilling, and we sourced strong yet super comfy elastics that can be recycled. With our bra closures, we included an additional row of hooks to increase adjustability and added some plush foam padding for added comfort and durability. Our goal is that iteration bras and undies will hold up, so you can  wear our bras and underwear longer. However, when the time comes to replace your underwear drawer, here are a few suggestions:

  • Re-use: We challenge everyone to think of ways to repurpose worn-out products in their everyday lives. Perhaps you could use some new cleaning wipes? We heard with good authority that modal fabric is excellent for cleaning wood and other delicate surfaces to avoid scratching. Maybe your throw cushions need a little extra stuffing? Is it time to try quilting? Cut them into strips and use them as plant ties or macrame? The possibilities are endless.
  • Trashie: Order a Take-Back bag to get rewarded for recycling your used clothing. Trashie has an advanced collection and sorting facility to get good clothes back into a new wearers' hands for an extended product lifecycle. In contrast, heavily worn clothes can be downcycled into rags and industrial insulation. They're also partnering with leading recycling innovators to use collected clothes as feedstock for new textile fibers.
  • Dream with Us: While it's not in place yet, we've been dreaming about creating an iteration recycling program. In the future, we plan to implement a recycling system to re-use as many of the salvageable bra components as possible. Just imagine being able to order a new bra and send your old one back to be collected, sorted, and deconstructed so the salvageable components could be recycled and used in a new bra. Are you seeing this circle?!

We'd love to hear your thoughts, feedback, and questions about sustainability. While we may not have all the answers, especially since the fashion industry can sometimes be like a big black box, we want to be as transparent as possible. So feel free to contact us at, and we'll do our best to get you the answers.



It·​er·​a·​tion; noun

Definition: A procedure in which repetition of a sequence of operations yields results successively closer to a desired outcome.

To our team, iteration is more than just a brand; it's a belief in continuous improvement and the power of collective creativity. We believe in designing and developing intimates through a collaborative community-driven process where every piece is a reflection of our community’s needs, desires, and values. We embrace the iterations of product development that make good products even better. We lean into sustainability, ethical production, and innovative design practices to ensure our creations not only look and feel great but also respect both people and the planet. Every product we launch is a testament to our commitment to create less but always better, together with you.


What sets iteration apart is our foundational commitment to co-creation, sustainability, and continuous improvement. Unlike traditional fashion brands, our product creation process is community-driven from the start. We deeply integrate customer feedback and ideas from the initial stages of design to the moment you get your hands on the product, ensuring that our products, packaging, and purpose truly resonate with YOU. 

We emphasize natural materials, ethical supply chains, and designing for longevity to reduce our environmental impact. While we prioritize natural fabrics, we also excel in innovation and functional design (so don’t expect another look-alike basic cotton bralette, because we value all the bells + whistles). Our unique approach combining a sustainable, yet innovative mindset ensures that each piece is not only thoughtfully engineered and stylish but also crafted to meet real-world needs and ethical standards.


Pop us an email at We promise to try and get back to email requests within 24 to 48 hours.


Send us an email at with your resume and a little bit about yourself. We may not be hiring currently, but we'll keep you in mind when the right opportunities arise.


Email our team at for any press inquiries. Please include what outlet you're publishing for and what kind of feature you'd like to do so we can see if there's a good fit.


We currently aren't offering wholesale opportunities, if you're interested in checking out our product, please purchase directly through our website.

Can't find what you're looking for?

Send us an email to tell us what's up and someone from our Customer Service team will get back to you as soon as possible. Be sure to include your order number (if you have one).

Please email us at