Variants, GTIN and availability in Shopping feeds

Variants, identifiers and availability are the most common source of disapprovals and duplicates in Shopping feeds. Modelling them well from the start avoids errors that are hard to diagnose later.

Variants: the role of item_group_id

A product with sizes and colours is represented as multiple separate items, one per variant, joined by the same item_group_id. Each variant has:

• a unique id;
• the same item_group_id as the logical "parent product";
• distinctive attributes (color, size, etc.);
• its own price, availability and identifiers.

A common mistake is to merge variants into a single item or, conversely, to forget the item_group_id and make them appear as unrelated products.

GTIN, MPN and brand

Case	Required identifiers
Product with an official GTIN	gtin (+ brand)
Product without a GTIN	mpn + brand
Own-brand product	identifier_exists set correctly

Wrong identifiers prevent product matching and reduce visibility. Validate them at the source: GTIN length and format, consistency with the brand, uniqueness.

Availability and price

availability must reflect the real state (in stock, out of stock, preorder) and be updated quickly: a product shown as available but sold out hurts experience and reputation. The price in the feed must match the page, including any sale_price and its dates.

Updating volatile fields

Price and availability change often. Handle them with incremental updates (event-driven or API) rather than relying only on the periodic full feed, so changes propagate in minutes, not hours.

Validation before sending

• each variant has item_group_id and consistent distinctive attributes;
• identifiers follow the category format and rules;
• availability and price are consistent with the product page;
• no duplicate id values.

Common mistakes

• variants without item_group_id treated as distinct products;
• wrong GTINs or GTINs reused across different products;
• stale availability and overselling;
• feed price different from the site price.

Conclusion

Variants, GTIN and availability are the details that separate an approved feed from one full of errors. Modelling variants with item_group_id, curating identifiers and updating volatile fields incrementally is the foundation of a reliable Shopping presence.