Size Advice: bonprix introduces its own AI feature for precise size recommendations

With a clear focus on customer satisfaction, bonprix is setting a new standard in digital size advice for women’s clothing: the AI-based feature Size Advice recommends a suitable size to existing customers in the German web shop and app – without them having to enter their measurements or upload photos of themselves. Since the rollout in October 2025, bonprix has been able to reduce the return rate in the women’s outerwear range by more than two percentage points when using Size Advice.

Finding the right clothing size is one of the biggest challenges when shopping online. Many solutions require customers to actively provide data such as their height and weight. bonprix has deliberately chosen a different approach: existing bonprix customers do not have to do anything. Size Advice combines individual purchase and return history with detailed item data, such as material specifications and product measurements, and uses this to calculate a reliable size recommendation in real time. The underlying AI model only makes a recommendation if the forecast accuracy is sufficiently high. The recommended size then appears automatically on the product page. The feature was developed in-house by a team of AI experts and programmers at bonprix.

“Artificial intelligence opens up new opportunities for online retailers to significantly improve the shopping experience while operating more efficiently,” comments Matthias Wlaka, Chief Technology Officer at bonprix. “With Size Advice, we are therefore using AI where it creates added value at the decisive moment. When existing customers find their correct size straight away, it is not only convenient, but also resource-saving and thus groundbreaking for e-commerce.”

Measurable effect: significantly reduced return rate

Size Advice went live in May 2025 for 20 per cent of existing customers in Germany and, following a successful test phase, for all existing customers in October 2025. The result: the return rate for women’s outerwear products among customers who used Size Advice fell by more than two percentage points. The feature therefore has a positive impact on one of the biggest cost factors in e-commerce. Fewer additional transport routes are required, and every return avoided also strengthens customer loyalty.

“Our goal was to develop a solution that works reliably without requiring customers to actively enter sensitive personal data,” states Sascha Netuschil, Domain Lead AI & Data Science Services at bonprix. “Based on existing article and transaction data, we have developed an AI model that is capable of making accurate size predictions. With Size Advice, we are translating our data competence and AI expertise into real benefits for our customers.”

AI use at bonprix: further expanding personalised offers

The feature is aimed at existing customers in Germany who have already placed multiple orders with bonprix, maintain their sizes, purchase items primarily for themselves and have agreed to the use of personalised cookies.

bonprix plans to extend Size Advice to other product ranges such as lingerie and swimwear. A solution for new customers is also in the works. In the future, the AI feature will be more closely integrated with other personalisation products, for example through automatic size filtering in product recommendations.

With Size Advice, bonprix is underlining its strategic focus on data-driven personalisation. The focus is on concrete benefits for customers, efficient processes, sustainable business practices and responsible use of data.