Missing Size System
size_system tells Google which sizing convention your size values use — US, UK, EU, IT, FR, DE, JP, CN, AU, BR, or MEX. A 'size 38' means different things depending on the system: US shoe size 38 is about a women's 7.5, EU size 38 is a men's 5.5 in shoes and a women's small in clothing. Without size_system, Google applies the target country's default interpretation, which may not match your actual sizes — especially for international feeds or sellers using non-local sizing.
Missing value [size_system] (recommended attribute)Impact: Missing size_system is a Warning — it doesn't disapprove products but it causes sizing confusion for international shoppers. Without size_system, Google assumes your sizes use the default sizing convention for your target market, which can result in German shoppers seeing US sizes as German sizes. This causes returns (wrong size), disappointed shoppers, and reduced conversion.
Root Causes
- 1Your feed template doesn't include size_system — it's recommended but not required, so default templates often omit it.
- 2You sell to multiple countries but use one size system (e.g., US sizes) across all feeds — without size_system, foreign feeds misinterpret.
- 3You sell European brands in the US market using EU sizes but don't specify size_system = 'EU' so US shoppers see confusing size numbers.
- 4You sell across regions and each region has its own size system but your feed doesn't differentiate.
- 5You have UK sizes (which differ from US sizes for both shoes and clothing) but default is assumed to be US.
Fix by Platform
- 1Add a size_system metafield: Settings → Custom data → Products → Add definition. Namespace: 'google', Key: 'size_system', Type: Single line text.
- 2Set value per product based on what size system your sizes use: 'US', 'UK', 'EU', 'IT', 'FR', 'DE', 'JP', 'CN', 'AU', 'BR', 'MEX'.
- 3For stores with a consistent size system across the catalog: use your feed app's static default value. Example: all products are US sizes → default size_system = 'US'.
- 4For multi-region feeds: use country-specific feeds with different size_system values. A feed targeting US with US sizes uses size_system = 'US'; a feed targeting Germany with EU sizes uses size_system = 'EU'.
- 5For import from European suppliers: set size_system = 'EU' on those products and ensure your size values are in EU sizing (e.g., 38, 40, 42 for shoes).
{{ product.metafields.google.size_system | default: 'US' }}When This Doesn't Apply
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Frequently Asked Questions
What are the valid size_system values?+
Exactly 11 values: 'US', 'UK', 'EU', 'IT' (Italian sizing), 'FR' (French), 'DE' (German), 'JP' (Japanese), 'CN' (Chinese), 'AU' (Australian), 'BR' (Brazilian), 'MEX' (Mexican). Lowercase also works ('us', 'eu', etc.). Other country codes or sizing systems aren't supported. Use the closest match if your sizing doesn't fit these exactly.
I sell in the US but my brand uses European sizes — what size_system do I use?+
size_system = 'EU' (or 'IT'/'FR'/'DE' if that's the specific system). The size_system describes YOUR sizes, not your target market. If you're selling EU-sized Gucci shoes in the US, set size_system = 'IT' (Italian — Gucci's native sizing) and submit sizes like '38', '40', '42'. US shoppers understanding they need to convert from EU sizing is part of the product reality — misrepresenting sizes as US just because your market is US causes returns.
My products have both US and EU sizing on the label — which do I submit?+
Pick one system for consistency across your feed. Best practice: use the sizing most commonly used in your target market. For US-targeted feeds, use US sizes with size_system = 'US'. For EU-targeted feeds, use EU sizes with size_system = 'EU'. If you want to serve both markets, create separate feeds for each country with appropriate size conversions.
What's the difference between EU, IT, and FR size systems?+
They all use similar numeric scales but have subtle differences for specific categories. EU is the general European sizing (dresses 34/36/38/40 equivalent). IT (Italian) is used primarily for men's suits and shoes (slightly different from generic EU). FR (French) is similar to IT but with slight variations in men's sizing. For most purposes, EU is the safe default — use IT or FR only if your products genuinely use those specific systems (commonly for luxury Italian or French brands).