Attribute Guide
shipping_weight Attribute in Google Shopping: Weight-Based Shipping Guide
Complete guide to the shipping_weight attribute in Google Merchant Center. Allowed units (lb, oz, kg, g), how Google uses weight for shipping calculations,…
Cast Iron Dutch Oven — 5.5 Quart
Weight enables accurate carrier rate calculation → correct shipping cost shown → no price surprise at checkout → lower abandonment
Cast Iron Dutch Oven — 5.5 Quart
Weight not provided → GMC cannot calculate weight-based shipping → shipping cost either missing or estimated incorrectly → inaccurate price shown to shoppers
When Merchant Center is configured with weight-based carrier shipping rates, shipping_weight is used to calculate the exact shipping cost per product. Without it, Google falls back to a flat rate or shows no shipping estimate — both lead to checkout surprises and abandoned carts.
What is the shipping_weight attribute?
The shipping_weight attribute specifies the weight of a product as used for shipping cost calculations. It is submitted as a numeric value paired with a unit (lb, oz, kg, or g). Google uses this value to calculate shipping costs when you have configured weight-based carrier shipping rates in Merchant Center.
For merchants using flat-rate or custom table-rate shipping, this attribute has no functional effect. For merchants integrated with real-time carrier rate APIs (UPS, FedEx, USPS, and similar) in Merchant Center, accurate shipping_weight is necessary to display correct shipping costs in Shopping listings — a key factor in purchase decisions for heavy items.
Technical specifications
| Feed name | shipping_weight |
| Required | Optional — required when using weight-based carrier rate configuration in Merchant Center |
| Format | Numeric value + space + unit: 3.6 kg, 7.9 lb, 250 g, 12 oz |
| Allowed units | lb, oz, kg, g |
| Value range | Must be a positive number. Decimal values are accepted. |
| Visible to shoppers | Indirectly — affects the shipping cost displayed in product listings |
When shipping_weight is and is not used
| Weight-based carrier rates (UPS, FedEx, USPS, etc.) | Used — Google queries carrier API with this weight to calculate shipping cost per destination |
| Flat-rate shipping | Not used — same rate applies regardless of weight |
| Table-rate shipping (price brackets) | Depends — if your table uses weight brackets, this attribute is used |
| Free shipping | Not used |
| Shipping excluded from feed (configured separately) | Not used |
Rules
-
Must use exact unit strings:
lb,oz,kg, org— no abbreviation variants -
Value must be positive — zero or negative values are invalid
-
Include a space between the numeric value and the unit:
3.6 kgnot3.6kg -
Decimal separator must be a period (
.), not a comma (,) — even for European-locale feeds -
Reflect packaged shipping weight, not just bare product weight
Best practices
-
Use kg for all products in EU/UK/AU feeds — metric units are the standard; using lb for European feeds causes no errors but is inconsistent with your carrier’s billing unit and may cause confusion.
-
Source weights from your logistics or fulfilment system — the most accurate weight data is typically in your warehouse management system or carrier-weighed outbound data. PIM/catalogue weights are a good second source but may reflect bare product weight rather than packaged weight.
-
Update when packaging changes — if you change packaging and the shipping weight changes meaningfully (e.g., switching from heavy gift boxes to lightweight poly mailers), update
shipping_weightaccordingly to keep shipping cost estimates accurate. -
Cross-reference with your carrier invoices — periodically check that your submitted
shipping_weightvalues align with the weights your carrier is actually billing. Systematic discrepancies indicate your feed data needs updating.
Common mistakes
-
Using unsupported unit strings: “lbs”, “kgs”, “gr”, “gram”, “kilogram” — all rejected
-
Missing space between value and unit:
3.6kginstead of3.6 kg -
Using comma as decimal separator:
3,6 kg— must use period -
Submitting bare product weight instead of packaged shipping weight
-
Not submitting when weight-based carrier rates are configured — causes missing or inaccurate shipping cost display
-
Using zero as a placeholder for “I don’t know” — zero weight is invalid; omit the attribute if the weight is unknown
Frequently asked questions
What units are allowed for shipping_weight?
lb (pounds), oz (ounces), kg (kilograms), and g (grams). The value must be a positive number followed by the unit, with a space between them: 3.6 kg, 7.9 lb, 250 g, 12 oz. Do not use abbreviations like "lbs", "kgs", "gr", or "gram" — only the exact supported unit strings are accepted.Is shipping_weight the same as the product's actual weight?
shipping_weight is the weight used for shipping cost calculation, which may include packaging. For light products with bulky packaging, the dimensional weight (volumetric weight) charged by carriers may exceed the actual product weight. Ideally, shipping_weight should reflect the weight your carrier uses to bill you — typically the packaged weight of the item ready to ship.When is shipping_weight actually used by Google?
shipping_weight is used when you have configured weight-based carrier shipping rates in Merchant Center (under Shipping settings — selecting a carrier like UPS, FedEx, or USPS and choosing weight-based pricing). In this setup, Google queries the carrier API with the product weight to calculate the shipping cost for the shopper's location. If you use flat-rate or table-rate shipping, shipping_weight has no effect.What is the maximum allowed shipping_weight value?
shipping_weight, but values above 2,000 lbs (approximately 907 kg) may cause validation issues, as most carrier APIs do not support single-shipment weights at that scale. For heavy freight items, verify that your carrier integration in Merchant Center supports the weight range. Extremely low values close to 0 may also cause calculation issues.Does shipping_weight affect SEO or Shopping ad ranking?
shipping_weight does not influence search matching, auction priority, or impression share. Its impact is indirect: accurate shipping weight enables accurate shipping cost display, which reduces checkout surprises and cart abandonment. Inaccurate or missing shipping costs are a significant source of checkout friction, particularly for heavier items where shipping can represent a meaningful percentage of the total order value.Can Boostora populate shipping_weight automatically?
shipping_weight values that exist in your structured product data (PIM, ERP, or catalogue). Boostora does not physically weigh products or estimate weights from product descriptions — weight data must come from your source system. If your feed is missing weights, the correct source is your product catalogue, logistics system, or your manufacturer's specifications.