What is a Size Chart?

A size chart is a structured reference that maps a garment or product size to body or product measurements. It usually appears as a table opened from a link next to the size selector on a product detail page, and it translates label sizes such as S, M and L or numeric grades into centimetres or inches. Size charts exist because sizing is not standardised across brands, regions or product groups. Their purpose is to support the choice of a correct size before an order is placed, which lowers the share of orders that come back as size related returns.

Definition

A size chart can be generic for an entire catalogue, specific to a product category, or specific to a single style whose fit deviates from the house standard. The measurement basis has to be stated: body measurements describe the wearer, product measurements describe the flat item, and mixing both produces inconsistent results. Regional conversion tables cover differences between sizing systems and are required for cross border assortments. Common weaknesses are charts delivered only as images, which are unreadable for assistive technology and for translation, charts that ignore variant specific fit such as tall or petite lines, and charts that stay static while the underlying pattern changes.

Why it matters

In a composable setup the size chart is content, not layout: measurements belong in a product information system or a structured content source and are referenced by category, style or variant, so a single correction propagates everywhere. The storefront requests the chart as data and renders it as a semantic table with proper headers, which keeps it accessible, translatable and indexable. Switching between metric and imperial units is a client side transformation of the same data set. Because the chart is often opened in a modal, loading it on demand keeps the initial product page payload small while the reference itself stays cacheable at the edge for repeated use.

Use cases

The primary placement is next to the size selector on the product detail page, opened as a modal or accordion so the selection context is preserved. Category pages can surface a general fit guide for the assortment. Fit notes, for example an indication that a style runs small, belong next to the chart rather than inside it. After a purchase the same data supports return forms that ask whether an item was too small or too large, and that feedback refines future fit notes. Customer service uses the chart as a single reference. In return portals and exchange flows it supports the selection of a replacement size.

Related

Explore Returns Management (RMA) · Trust Signals.