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Originally Published by: Watson
Germany leads the world in product returns. For many, it’s become part of everyday life: order a package, try it on, send it back if it doesn’t fit, and repeat. But this cycle has a serious impact on the environment and it’s clear that something needs to change. The founders of SAIZ have an answer to the return problem: precise size recommendations using avatars, digitally measured garments, and a system that makes returns unnecessary. In this interview with watson, Marita Sanchez de la Cerda and Svenja Tegtmeier explain why traditional sizes like S and M are outdated, and how their approach is helping save hundreds of thousands of tons of CO₂.
Marita: Our focus is on sizing, as the name SAIZ already suggests. It’s all about sizing and fit. Throughout our careers in the fashion industry, we’ve seen that this is the biggest lever for driving real sustainability within the industry. Around 60% of returns happen because the fit isn’t right. That impacts not just the environment, but also profitability and production. So, we go straight to the root of the problem: smarter sizing to build a more sustainable industry.
Svenja: At SAIZ, we’ve developed several tools to improve sizing. Most are designed for our brand partners, but we also offer features for end customers. One example is our size recommendation tool, where you can create an avatar of your body - kind of like in The Sims. At the same time, we’re working on providing detailed product data and creating digital twins of garments that can be tried on by the avatar. That’s where our two AI’s: Product AI and Human AI come together.
“We believe labels like S or M are misleading. Within a single size, there can be differences of up to 15 centimeters across the fashion industry.”
Svenja: That’s true. The product photos are often styled with clips. The models wear samples that aren’t tailored to them, so the clothes are clipped in the back just for the shoot. That’s exactly why we want to offer more accurate information about how clothes actually fit and fall on real bodies.
Svenja: That’s one of the core issues: there are no universal industry standards. And even if there were, it’s still hard for brands to reproduce the exact same fit consistently. It’s really an art. So instead, our approach is to describe the actual fit of each item in detail for customers. We believe labels like S or M are outdated, as there can be up to a 15 cm difference within the same size. It might be more effective to group body types into categories with names like “Purple” or “Blue.”
Svenja: Exactly. There are many layers to this issue. That’s why sizing and fit is such a fascinating area. We’re working on a mathematical solution, but the problem also has so many emotional and social dimensions.
Marita: Our system gives manufacturers deep insights into their products, which improves the customer experience, builds trust and loyalty, and helps brands adjust their fits to reflect real measurements of what people actually wear - not what’s left sitting in warehouses or gets discarded at the end of the season.
Svenja: Last year, we measured around 300,000 products and provided size recommendations to about 300 million people. That helped save roughly 580,000 tons of CO₂ . That's about the same amount that all households in Hamburg emit over two years. The return problem involves more than just transportation; it also includes cleaning, repackaging, and emissions from delivery trucks and planes. Fast fashion brands sometimes just discard returns if the items are already “out of trend.” The fashion industry is the second most polluting in the world, largely due to these inefficiencies.
Marita: And that 7 - 10% is just the starting point. We’re only scratching the surface. In Germany, we believe return reductions of up to 50% are achievable.
Svenja: Fun fact: Germany ranks #1 in the world for returns. Retailer Otto helped establish this behavior early on, and our generation grew up seeing returns as normal. This actually makes it challenging for foreign brands to succeed here in Germany, they have to be equipped to handle that a high volume of returns.
“The fashion industry is undergoing a deep transformation, driven by the AI revolution.”
Svenja: Yes, we closely monitor our energy impact and calculate it annually. Just from the returns we prevent, our positive impact has already been offset 30,000 times. We train our AI models efficiently and don’t operate data centers like OpenAI, so our energy usage is relatively low.
Svenja: Absolutely. Sizing and fit are our core focus right now because that’s where the greatest impact lies. But we’re also exploring personalized online shopping and other areas. There are so many untapped data points related to fit and sizing that could unlock efficiencies across production, marketing, and logistics.
Marita: We’re also helping brands digitize and streamline outdated processes across the fashion industry and supporting them through this transformation.
Svenja: That’s key. The fashion industry is at the start of a deep transformation driven by AI. In the future, shopping will be much more personalized and social commerce focused. To stay competitive, brands need to structure and activate their data now. Those who don’t, risk falling behind - especially in an industry that already faces so many inefficiencies.
