Item group id for variants in Google Shopping

The item_group_id ties every variant of one product together. Each color and size combination is its own item with its own id, and the shared item_group_id tells Google they are the same product. Google then shows the best matching variant for each search and folds the rest into a swatch picker.

How this app fills it

• When a product has more than one variant, every variant gets the product's id as its item_group_id automatically.
• The value follows the same format family as your item ids, so groups stay stable as long as the id format does.
• Switching the feed to first variant only mode in the Metadata tab drops the grouping, since each product then sends one item.

Dos

• Send all variants with distinguishing attributes like color and size filled in. The group only works when variants differ visibly.
• Keep variant differences real. Variants in one group should differ by attributes like color, size or material.

Don'ts

• Don't group unrelated products under one item_group_id to pool their history. Google detects and penalizes it.
• Don't switch id formats mid flight. Groups are keyed to ids, and both reset together.
• Don't send identical variants that differ only in price.