How can apparel markup specify a size system and size group?

Definition: In Product structured data, size can contain a SizeSpecification. Its name identifies the product size, sizeSystem identifies the sizing convention, and sizeGroup describes a suggested apparel group such as regular, petite, or tall.

Key facts

• Google's merchant listing documentation accepts Text or SizeSpecification for size, gives “XL” and “medium” as examples, and says to specify at most one value.
• The same documentation defines name as a human readable size name, with “XL” as its example.
• It lists WearableSizeSystemEnumeration or Text for sizeSystem, including URL-form values for Australia, Brazil, China, Germany, Europe, France, Italy, Japan, Mexico, the United Kingdom, and the United States.
• It lists WearableSizeGroupEnumeration or Text for sizeGroup, allows at most two groups, and supports regular, petite, plus, tall, big, and maternity.
• Schema.org's SizeSpecification definition describes the type as size-related product properties that typically include a size code and can include sizeSystem and sizeGroup.

What does SizeSpecification represent?

Google's merchant listing documentation, updated 8 September 2026, uses SizeSpecification for the value of a product's size property. The page says that the type indicates the size of a product and points to Schema.org for its full definition. A product can therefore keep the shopper-facing size code in name while attaching the system and group as properties of the same object.

Schema.org describes SizeSpecification as size-related product properties. Its definition names name as the typical size code and lists sizeSystem and sizeGroup as optional properties. The type is therefore a structured value inside Product, rather than a separate product field for each part of a clothing size.

How do name, sizeSystem and sizeGroup differ?

name is the readable size label, such as XL. It identifies the size selected for the product. sizeSystem identifies the convention used to interpret that label. Schema.org describes a size system as a standard such as “GS1” or “ISO-EN13402”, a country code such as “US” or “JP”, or a measuring system such as “Metric” or “Imperial”.

Google documents URL-form enumeration values for the geographic systems and also says that short names without the URL prefix are supported. The standard URL form is more explicit in markup. Google's documentation gives https://schema.org/WearableSizeSystemUS for the United States and https://schema.org/WearableSizeSystemEurope for Europe.

sizeGroup describes a size segment or suggested audience for a wearable product. Schema.org gives “men's big and tall”, “petite maternity”, and “regular” as examples of combined or individual groups. Google supports six group values and says that at most two groups can be provided. Its documented URL form is https://schema.org/WearableSizeGroupRegular, with the corresponding short name WearableSizeGroupRegular also supported.

What can the JSON-LD look like?

Place the three properties inside the SizeSpecification object used as the Product's size value. This example uses Google's documented United States size system, one documented group, and the human-readable name XL.

{
  "@context": "https://schema.org/",
  "@type": "Product",
  "name": "Cotton shirt",
  "size": {
    "@type": "SizeSpecification",
    "name": "XL",
    "sizeSystem": "https://schema.org/WearableSizeSystemUS",
    "sizeGroup": "https://schema.org/WearableSizeGroupRegular"
  }
}

The value of name is the product size label. The system and group use Schema.org URL values that Google lists in the merchant listing documentation. When a size has two applicable groups, Google permits two sizeGroup values; the page also recommends standard Schema.org enumeration values because other search engines may not understand the text forms.

How should the markup be checked?

Google says to validate merchant listing markup with the Rich Results Test and fix critical errors. It also documents the URL Inspection tool for testing how Google sees a page after deployment, and says the page must be accessible to Google rather than blocked by robots.txt or a noindex tag. Check that the rendered size object contains the intended name, one supported sizeSystem, and no more than two supported sizeGroup values.

Related terms

• Product structured data
• ProductGroup structured data
• How should product variants be represented in structured data?

FAQ

What should SizeSpecification.name contain?

Use the human readable size label for the product, such as XL. Google describes name this way in its merchant listing documentation.

Can sizeSystem be a text value?

Yes. Google lists Text as an accepted type and says that short names without the URL prefix are supported. The same documentation recommends standard Schema.org enumeration values because other search engines may not understand text values.

How many sizeGroup values can be provided?

Google allows at most two size groups. Supported groups include regular, petite, plus, tall, big, and maternity.

Sources

1. Google Search Central, "Merchant listing (Product, Offer) structured data", 2026-09-08
2. Schema.org, "SizeSpecification - Schema.org Enumeration Type", 2026-09-16

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