Size System [size_system] Field for Product Feed

Optional but recommended for accurate size filtering (Google & ChatGPT)

The size_system attribute specifies the sizing standard (country or region) used for your product. It ensures that sizes are interpreted correctly by Google and shown accurately in filtered search results.

When to use

• Optional for all products, but recommended for apparel and footwear.
• If you submit a value for size, you should also submit the corresponding size_system.
• Helps avoid mismatches when sizes vary between regions.

Supported values:

• AU (Australia)
• BR (Brazil)
• CN (China)
• DE (Germany)
• EU (Europe)
• FR (France)
• IT (Italy)
• JP (Japan)
• MEX (Mexico)
• UK (United Kingdom)
• US (United States)

Format

• Type: Text (one of the supported values)
• Repeated field: No
• Schema.org property: Product.size — WearableSizeSystemEnumeration

File format examples:

Minimum requirements

• Use only supported country codes.
• If omitted, Google defaults to the target country’s standard which may not be correct for your product.
• Do not submit custom or unsupported values.

Best practices

• Always submit for apparel and shoes to avoid incorrect size display.
• Match the size system to your product’s sizing label.
• Submit size alongside size_system for complete sizing info.
• If relevant, also provide size_type and gender to enhance filtering.

SEO Tip

Correct size system data improves shopper trust and prevents returns by ensuring users see the right sizing for their region.

Official Source : https://support.google.com/merchants/answer/6324502