Context - This is a proposal from Google based on our experience consuming schema.org Offer markup and working with similar data from online merchants. If it were accepted, it would make it easier for us and others to understand shipping dimensions (and associated delivery fees) for products sold online.

Proposal - Schema.org supports the specification of product dimensions through properties depth, width, height, and weight. However, delivery dimensions of a product can be substantially different from the product's dimensions itself, for example flat-pack furniture that needs to be assembled after delivery, or fragile items that require heavy protective materials for transport. Such shipping dimensions can also vary depending on the merchant, so are typically related to an Offer and not a Product. We therefore propose to add 4 new properties shippingWidth, shippingHeight, shippingLength, and shippingWeight. All 4 properties will be of type QuantitativeValue and will be for use on class Offer.

Alternatives

• Instead of adding 4 new properties we could add the existing depth, width, height, and weight properties for use on Offer (currently these are only available on Product). However, this might be ambiguous and cause confusion.
• A more flexible alternative would be adding the 4 existing properties depth, width, height, and weight for use on OfferShippingDetails, which allows for multiple packaging options for the same product. However, this might be unnecessary since packaging is typically the same independent from the shipping destination.
• Yet another alternative would be adding a new ShippingDimension structured type (to be used on Offer using a new property), and adding the 4 existing dimension properties for use on this new type.
• Instead of the "shipping" prefix we could decided to use a "package" or "shippingPackage" prefix for the property names.