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Shopify Package Sizes: Set Packages So Rates Come Out Right

Updated , first published · 4 min read

Shopify package sizes matter because checkout rates are calculated from them. Shopify uses your store default package for every product that has no package of its own, and with weight-based rates it adds the box’s weight to the products. You can also give each product its packed dimensions, and for carrier-calculated rates Shopify then packs each shipment into the smallest of your saved boxes that fits. Set those two things correctly and the shipping a customer pays gets close to what the label costs you.

Everything below comes from Shopify’s Help Center page on setting up packages (read October 23, 2026).

How packages affect checkout rates

Three rules decide which box Shopify uses when it calculates a rate:

  1. A product’s own package, for single-item orders. A package assigned to a variant (Package when shipped alone) overrides the default, and it takes priority for a single-item order.
  2. Packed product size. If every product in the shipment has a packed product size and your saved boxes include one that fits, Shopify packs the items into the smallest fitting box for carrier-calculated rates. Only packages of the Box type are used this way; envelopes, soft packs, flat-rate and carrier packages are not. If an order ships from two locations, each location’s items get their own box.
  3. Otherwise, the store default package. It is used when any item lacks a packed size, when the default is not a box, when no saved box fits, when you have a large number of saved boxes, or when an order has many items.

The default package also adds weight. Shopify’s example: with a default box weighing 0.1825 kg and weight-based rates of $3 up to 4.99 kg and $5 from 5 kg, a 4.9 kg order becomes 5.0825 kg and pays $5. Weigh your real empty box.

Two more details: measure the outside of your boxes, because carriers price by outside dimensions while their own size charts often give inside dimensions; and if you set a carrier package (for example a UPS box) as the default, checkout shows only that carrier’s rates.

Add packages and choose the default

  1. Go to Settings > Shipping and delivery.
  2. In the Packages section, click Add package.
  3. Name it, choose the Package type, enter its outside dimensions and its empty weight.
  4. Check Use as default package if this is the box you ship most often.
  5. Click Add package.

For carrier boxes, choose Carrier package, then USPS package or UPS package and the package type; their dimensions are fixed. You can change the default later with Set as default on another package. The default cannot be deleted until another package is the default.

Add the boxes you actually stock, not every size a supplier sells. Three or four boxes matched to your range give Shopify enough choice, and Shopify notes that a large number of saved boxes makes it fall back to the default.

Give products their own package or packed size

Packed product size. Open a product (or a variant), make sure Physical product is on in the Shipping section, and enter the length, width and height after packing, with the unit. All three are needed, or nothing is saved. You can set packed sizes in bulk in the bulk editor or by product CSV. Start with your best sellers and anything bulky.

Package when shipped alone. In the same Shipping section, pick a package from Package when shipped alone, or create one with Add new package. Use it for items that always ship in a specific box (a poster tube, a boxed lamp). Remember it only applies when the item is ordered alone; in mixed orders, packed sizes or the default decide.

Fixed product bundles have no packed size of their own; each product in the bundle is packed by its own size.

Suggested packages when buying labels

When you buy a label in Shopify, a Suggested package may already be selected, based on the package you chose for similar orders before. The more labels you buy, the more orders get a suggestion. If no suggestion exists, the default package is selected, so a correct default also saves clicks at the label screen.

For how packages fit into your rate strategy, see Shopify shipping strategy and reduce shipping costs; for what goes inside the box, unboxing experience. The shipping and returns hub has the rest.

FAQ

Why does Shopify use the wrong box size at checkout? Shopify uses the store default package when any product in the cart has no packed product size, when no saved box fits, or when the order has many items. Add packed sizes and the boxes you use.

Can I set a different package for each product in Shopify? You can assign a package to each variant, but Shopify uses it only for single-item orders. For mixed orders, add packed product sizes so Shopify picks the smallest saved box that fits.

Does the package weight count toward shipping rates? With weight-based rates, the default package’s weight is added to the products’ weight, which can move an order into a higher weight band.