Item Weight Unit [item_weight_unit] Field for Product Feeds

Optional for ChatGPT

The item_weight_unit attribute defines the unit of measurement used for a product’s weight.

Although optional by default, this field becomes required whenever the weight attribute is provided.
It ensures that ChatGPT correctly interprets the product’s physical weight and avoids ambiguity between measurement systems.

This field is used exclusively by AI systems and does not affect how products are displayed on your website.

When to use

Use this field whenever you provide a value for the weight attribute.

Without item_weight_unit, the weight value may be considered invalid or ignored by ChatGPT.

• [item_weight_unit] accepts:
  • kg → Kilograms
  • lb → Pounds
  • g → Grams
  • oz → Ounces

Format

• Type: String
• Accepted values: kg, lb, g, oz
• Repeated field: No
• Schema.org property: Not applicable (AI-only field)

Examples:

Minimum requirements

Note: If weight is provided, item_weight_unit becomes mandatory.

• Always specify item_weight_unit when providing weight.
• Use a valid and consistent unit for all weight values.
• Do not provide a weight value without its corresponding unit.
• Avoid mixing different weight units for the same product.

SEO / AI Tip

Accurate weight information helps AI systems:

• compare products more precisely,
• estimate shipping and fulfillment constraints,
• reduce ambiguity in conversational commerce.

Providing both weight and item_weight_unit improves AI understanding and trust, especially for physical products.

For best results, combine this field with:

• [weight]
• [dimensions_unit]
• [length], [width], [height]

Official Source: ChatGPT Product Feed Specs