ID [id] Field for Product Feed

Required for each product (Google & ChatGPT)

The id attribute is used to uniquely identify each product. It’s not visible to customers, but it’s essential for feed tracking, bid targeting, and performance analysis. We recommend using your product SKU.

When to use

Use the id field for every product. It is a required field to differentiate products within your feed and track them consistently across platforms.

Format

Follow these formatting guidelines to ensure Google correctly reads your product IDs:

• Type: Unicode characters (Recommended: ASCII only). Alphanumeric, underscores _, and dashes -.
• Limits: 1–50 characters
• Repeated field: No
• Schema.org property: Product.sku

ID formatting examples:

Minimum requirements

Note: IDs help track product history in Google Ads and Merchant Center. Do not change them arbitrarily.

• Submit a unique ID for each different product.
• Do not change IDs once assigned. This maintains product history.
• Use the same ID for a product across countries/languages.
• Avoid using casing (e.g., ABC123 ≠ abc123). Use unique strings instead.
• Do not reuse IDs for different products or variants.
• Avoid whitespace and invalid Unicode characters (e.g., U+200D).

Best practices

• Use SKUs as IDs when possible.
• For Vehicle Ads in the UK, use the Vehicle Registration Mark (VRM).

Official Source : https://support.google.com/merchants/answer/6324405