Is Design By Si Fast Fashion? How Ethical & Sustainable is Design By Si
Yes, Design By Si fits the fast fashion model. It's a Danish online store selling trend-led clothing, it launches new collections continuously, and most pieces sit under $100, which is the shape of fast fashion as the term is normally used.
One distinction matters before you judge it. Design By Si doesn't make its own clothes. It imports and sells them, and it publishes nothing about who produces them, where, or what they're made from. Here's what's documented on its own site.
Who Runs Design By Si and What It Sells
Design By Si is a Danish clothing, footwear and accessories retailer, registered as Designbysi ApS in Køge, Denmark under CVR 37079227. Isabella Laybourn founded it in 2016, and the brand's about page tells the origin story plainly. She started selling jewellery through Instagram direct messages, posting orders herself. Within months she was importing clothing and accessories inspired by trends she'd seen on social media, and within a year the hobby had become a full webshop.
That origin is still the business model. Design By Si buys in stock and sells it, describing its range as a selection of clothes chosen to follow current trends at accessible prices. Nowhere does it claim to design, cut or manufacture anything.
Why Design By Si Counts as Fast Fashion
Fast fashion is cheap, quickly replaced, trend-driven clothing sold in high volume and designed to be worn for a season rather than years. Design By Si matches on every part of that description, and you don't need an insider to prove it. The evidence is on the brand's own storefront.
Its drops page lists 20 separate collections, including The Paris Edit, French Summer Affair, Red City Collection, Tone Theory and Outdoor Dreams, plus a further drop marked as coming soon. The Danish text on that page sets out the cadence in the brand's own words: it launches collections "løbende og hyppigt" (continuously and frequently) with themes based on trends and its own ideas. No fixed release schedule is published anywhere, so we can't tell you it drops weekly or monthly. What's on the record is 20 themed launches from a single small retailer.
Volume tells the same story. The Nyheder page, which is the new arrivals feed, held 536 products when we checked in August 2026. Pricing on the English store runs from a Sola bracelet ($20) and the Beate ribbed tank top ($32) up through the Flora maxi dress ($79), the Johanne wide-leg jeans ($102) and the Jujava trenchcoat ($131). On the Danish site that same trenchcoat is 669 kr, jeans are around 499 kr, and knitwear sits between 349 and 419 kr. That's high street pricing.
What Design By Si Doesn't Publish
Design By Si publishes no information about materials, factories, production countries, wages or environmental impact. We looked at the homepage, the about page, the drops page and the new arrivals feed across both the Danish and English stores, and found nothing on any of them.
It's worth being careful about what that means. An absence of disclosure doesn't tell you conditions in a factory are bad, because it doesn't tell you anything about the factory at all. What it tells you is that a shopper who wants to know what a dress is made from, or who sewed it, can't find out from the brand. There's no supplier list, no audit summary, no impact report, and no third-party certification claimed anywhere we could find.
The silence is specific to production. Design By Si publishes its consumer terms clearly enough, with a 14-day return window, one to three day dispatch from Denmark, and free Danish shipping over 600 kr. A brand that documents its returns policy in detail and its supply chain not at all has made a choice about which questions it answers.
Brands That Publish What Design By Si Doesn't
If the missing information is what bothers you, these three sell comparable everyday clothing and put the details on the record.
Organic Basics
Organic Basics is the closest like-for-like swap here, because it's also Danish. Designed in Copenhagen and shipped from a Danish warehouse, it publishes a factory list naming its production countries, including Indonesia, India, Egypt, Vietnam, Thailand, Turkey and China. It names its materials rather than leaving them blank, using organic cotton, recycled nylon, responsible wool and TENCEL, and it publishes annual impact reports alongside a carbon footprint figure on individual products. The Flex Tee (€36), Flex Tank Top (€32) and True Heavy Long Sleeve Tee (€41) are the everyday starting points.
Tentree
Tentree is a certified B Corp, and it links to its own profile on bcorporation.net rather than asking you to take the badge on faith. It maintains separate published pages on ethical manufacturing and materials, and it plants ten trees for every item sold, with over 117 million planted so far against a stated goal of one billion by 2030. Women's tops and basics run roughly $50 to $80, with outerwear from about $100. The clothing is casual and built for wear rather than for a single trend cycle.
Reformation
Reformation covers the trend-led dress territory that Design By Si occupies, at a higher price. It publishes a 2025 sustainability report and runs RefScale, which puts environmental data against individual garments, alongside published pages on circularity. The Hugo Knit Dress ($198) and Opaline Silk Dress ($248) show where the pricing lands. You're paying several times a Design By Si dress, and in exchange you can read what the fabric is and what the brand claims it cost the planet.
Frequently Asked Questions
Is designbysi.com the same brand?
No. The Danish clothing brand trades at designbysi.dk and designbysi.se. The domain designbysi.com belongs to Design By Si LTD, an unrelated British graphic and motion design studio whose portfolio site lists client work for ASOS, Tesco and Monzo. It sells no clothing, and nothing in this article applies to it.
Where are Design By Si's clothes made?
The brand doesn't say. Design By Si publishes no production countries, no factory list and no supplier information on either its Danish or English store. Its about page describes importing stock inspired by social media trends, which tells you it buys finished goods rather than manufacturing them, but it stops short of naming where those goods come from.
Why is Design By Si cheap?
A trenchcoat at 669 kr and a tank top at $32 reflect a buying-and-reselling model rather than an in-house production one. Design By Si sources finished stock and moves it in volume, with 536 items sitting in the new arrivals feed alone. It publishes no material composition or production cost breakdown, so any explanation beyond the model itself would be guesswork.
Does Design By Si use sustainable materials?
There's no way to tell from the brand's site. Design By Si makes no sustainability claims at all, which is different from making claims that don't hold up. It publishes no fibre content, no certifications such as GOTS or the Global Recycled Standard, and no environmental targets. If material composition matters to you, this isn't a brand you can evaluate before you buy.
What to Check Before You Buy
Twenty trend drops and a 536-piece new-in feed settle the fast fashion question. The one left is your own comfort level with buying clothes that arrive with no published fibre content and no named supplier. Plenty of shoppers are fine with that, and a 669 kr trenchcoat has an obvious appeal. Just know that's the trade you're making.
If you want a repeatable way to sort real disclosure from marketing language, our guide on how to tell if a brand is sustainable walks through the documents worth looking for. We ran the same checks on a much larger trend importer in is Taobao fast fashion, and more brand breakdowns are in our articles.
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Written by
Spencer Lanoue
