What happens when a product has no weight?

On a rate card that prices by weight, its parcel takes the zone's last price, the one for the heaviest parcels. The order is also flagged. nouz never guesses a weight. A made-up weight could misprice every order with that product without telling you. The last price errs on the expensive side, and it says so.

Without a weight, a parcel cannot be put in a weight bracket. A bracket is one row of the rate card, like up to 2 kg. One unknown item makes the whole parcel's weight unknown, because a weight with a gap in it is not a weight.

A product Shopify left at its default of 0 g counts as unknown too. Every new Shopify product starts at 0 g, whether it weighs a gram or a kilo.

Size works the same way. On a rate card that prices by size, a product with no packaging size sends its parcel to the zone's last price. The order is flagged too. For the box a packaging rule picks, a product without a size counts as size 1 until you set one.

Weight and packaging size are yours, not Shopify's. Set them in the product's panel on the Products page. The affected days are then worked out again with the real value, and the flag clears. The Overview lists how many orders were priced without a weight or a size, under Needs your attention. Most gaps sit in a few products, so it is a short job. On the Products page, a dash in the Weight column means no weight.