A new report by Coresight Research and Alvanon, titled “Shifting the Size and Fit Paradigm,” reveals that sizing and fit issues remain the primary driver of online apparel returns, accounting for approximately 70 percent of all returns in the last 12 months.
With the U.S. online apparel and footwear market reaching $201.1 billion in 2025, an estimated 23.4 percent return rate translates to a staggering $47.1 billion in returned merchandise. The report’s authors said inconsistent or poorly governed sizing systems not only erode profit margins through reverse logistics and markdowns, but also fail to meet the needs of a diverse and evolving consumer base.
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“Sizing and fit represent a foundational opportunity for the apparel industry to address implications for returns, inventory alignment and customer satisfaction,” the authors of the report said. “These implications often stem from inconsistent or poorly governed sizing systems, including fragmented fit standards and ineffective communication to consumers.”
To help retailers and brands combat this costly issue, the report presented a three-pillar framework centered on “Sizing Intelligence,” which involves the capture and activation of body shape and sizing data to inform business and merchandising decisions. The pillars include establishing disciplined size and fit standards as a foundational layer, utilizing Product Information Management (PIM) as an operational backbone to maintain structured data and optimizing the Product Detail Page (PDP) to provide clear, actionable information to shoppers.
By way of a case study, the report noted that the brand Bershka successfully implemented these standards. “For example, Bershka, a sister brand of Zara, recently undertook a major refresh that included an overhaul of its sizing strategy and standards,” the authors of the report said. “In partnership with Alvanon, a data-driven sizing technology provider, Bershka identified the size range of its core customers, then used digital avatars and physical mannequin ‘twins’ to align its entire product range consistently across all its internal teams and suppliers—resulting in a 10 [percent] reduction in returns.”
The urgency for this shift is being accelerated by emerging market forces such as agentic commerce and the rise of GLP-1 medications. AI agents now increasingly mediate shopping, penalizing brands that lack structured, machine-readable sizing data.
“AI agents rely on structured, machine-readable data to evaluate and recommend products, effectively penalizing brands with inconsistent or incomplete sizing information,” the report noted. “As these agents increasingly mediate global commerce, retailers with poor data quality risk [losing] visibility and scaled decision errors.”
Simultaneously, a Coresight Research survey from November 2025 found that 72 percent of U.S. GLP-1 users have dropped at least one clothing size, highlighting a massive need for reliable size recommendations during frequent body transitions.
By grounding strategies in real customer data rather than “one-size-fits-all” assumptions, retailers and brands can build long-term loyalty and a sustainable competitive advantage in a rapidly changing landscape.
