Interview with global sizing expert Ton Wiedenhoff, Executive Director, Europe, Alvanon

With more than 35 years in the apparel industry, Ton Wiedenhoff, Executive Director Europe for the sizing and apparel technology company Alvanon, has helped hundreds of brands and retailers integrate transformative sizing standards and smarter processes into their value chains.

In this insightful interview for FashionUnited, he explains why sizing is a strategic business issue and how brands can use foundational data to increase their visibility and reach their sustainability and business goals in the agentic era.

Q:The fashion industry is facing no shortage of challenges. What concerns you most?

Ton: We still make too many clothes.

We have seen decades of over production - too many garments are being manufactured and too many being sold at discount or worse, ending up in landfill. My frustration is that while many brands and retailers are investing in sustainable practices and processes, many are still overlooking one of the biggest contributors to waste: making clothes that don’t fit real bodies.

A recent report we collaborated on with Coresight Research* shows the scale of the problem. Last year in the US alone, consumers returned over $47 billion of merchandise – and 70 per cent named size and fit as the reason for the return. That is a lot of frustrated customers, a lot of waste and a huge cost to brands.

Q: So what can companies do to address overproduction, waste and returns?

Ton: Go back to serving their specific consumer demographic - ‘one size’ will never fit all so it’s about defining what your customers look like, their size and shape, and then making clothes for those consumers.

It’s easier said than done. Making it happen requires leadership and a commitment to hard wire a brand’s specific sizing standards into its processes across the value chain. This usually means breaking down legacy silos and processes, defining and sharing a single source of sizing truth and making sure this is consistently applied to every garment and clearly communicated to the consumer.

Q: AI is transforming retail at an incredible speed. Is it helping or making things more complicated?

Ton: The answer is both.

The era of agentic commerce is here and it has already transformed the way many of us shop. AI agents rely on structured machine-readable data to evaluate and recommend products. If a brand’s sizing information is inconsistent or incomplete, AI agents won’t be able to recommend its products effectively. Even worse, if AI is working with inaccurate sizing data, it will simply recommend the wrong products more efficiently, making the returns problem even bigger! That’s why getting the foundational sizing right isn’t just an operational issue – it’s a strategic requirement for succeeding with AI.

Q: Is anyone using foundational sizing data in this way to benefit their businesses?

Ton: Absolutely.

Bershka, a sister company to Zara and part of the Inditex Group, has built its product development and e-commerce strategy around a clearly defined sizing range standard for its target consumer demographic.

Its designers, pattern makers, manufacturers and e-commerce teams refer to this core standard as their single source of truth. They use digital avatars and physical ‘twin’ mannequins based on that standard ensuring consistency across the value chain. It’s resulted in a ten per cent reduction in Bershka’s return rates and it shows what’s possible when foundational sizing data becomes central to the business.

Q: Beyond reducing returns, what other advantages does a strong sizing strategy deliver?

Ton: It will help designers make better decisions, improve assortment planning and merchandising, reduce guesswork, support more accurate inventory planning, minimise waste and enable better demand forecasting. The benefits extend across the value chain.

Q: It sounds rather complicated. Where should a company start?

Ton: The Coresight Research Report looked at exactly this and identified three core pillars to future-proof for sizing and fit: establish foundational size and fit standards; implement robust Product Information Management; and communicate sizing clearly through Product Detail Pages.

I’ve already talked about the importance of establishing foundational sizing and fit standards. What I should emphasise is that these core standards should be locked in for five to seven years. If they're continually adjusted, you can create ‘fit drift’, where sizing gradually changes over time. Customers lose confidence because they no longer know what size to buy. It takes time to achieve trust in a brand's fit.

Q: And so what of the second pillar, Product Information Management? Many apparel brands have those systems in place already?

Ton: Indeed. As an industry we already know how important PIM is to aligning processes. Product Information Management has become the operational backbone that connects fit strategy to execution across the apparel value chain. Once a brand has established its size and fit standard they need to translate that standard into structured, usable product data such as garment measurements, intended fit profiles, fabric composition and stretch characteristics.

Just as important is ‘ownership’. Technical design, product development and ecommerce teams all need to agree and ‘own’ how fit information is created, validated and maintained.

The most advanced organisations create feedback loops. They analyse returns, customer reviews and regional buying patterns to identify recurring sizing issues, then feed these insights back into future product development. That creates continuous improvement rather than repeating the same mistakes.

Q: And so, to the third pillar consumer experience and the Product Detail Page. How can companies accurately communicate their sizing and fit strategies to their customers especially as predictive sizing tools and virtual try-on become more common?

Ton: For consumers, the Product Detail Page, is the moment of truth.

Consumers need clear, practical information that helps them understand how a garment will fit their body. That means detailed measurements, clear descriptions of intended silhouette and fit, and information about how fabrics behave when worn.

Showing garments on different body shapes helps communicate aspects of fit that measurements alone cannot capture, including drape, volume and movement.

Customer reviews are equally valuable, particularly when they are filtered by body type, height or fit preference. Combined with accurate model measurements and comparative sizing guidance, they help consumers buy with much greater confidence.

Q: Finally, looking ahead, what should fashion businesses be focusing on now?

Ton: Big tech may own the AI platforms, but apparel brands and retailers own the proprietary data that serves their customers and businesses. That’s where competitive advantage lies.

To succeed in the AI era, the need for clean, machine-readable fit data is an imperative. Accurate agentic recommendations depend entirely on the quality of the information we as an industry provide.

Success in the AI era won’t be determined by who had the best visual AI. It will be determined by who has the best and most accurate foundational data and that is something every brand can control.

*Coresight Research Report May 2026 'Shifting the Size & Fit Paradigm: A Three Pillar Framework to Reduce Returns and Future-Proof for Agentic Commerce’