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The shipping label goes on the outside of the box for the carrier: addresses, barcode, and service details. The packing slip goes inside for the recipient: a list of what is in the box, with prices left off. One tells the box where to go; the other tells the person opening it what they got.
| Shipping label | Packing slip | |
|---|---|---|
| Audience | The carrier's machines and handlers | The person opening the box |
| Placement | Stuck on the outside of the box | Placed inside the box (or in a pouch on the outside, but never the only identifier) |
| Contents | To and from addresses, barcode, tracking number, service level, weight | Item names, quantities, SKUs, order number; prices omitted |
| Required? | Yes: the box cannot ship without it | No, but expected: customers use it to check their order |
| Privacy | Visible to everyone who handles the box | Seen only by the recipient |
The shipping label is a machine-readable instruction. Its barcode is what sorting equipment reads at every handoff, which is why a clean, flat, fully printed label matters more than anything handwritten: smudged or wrinkled barcodes get kicked to manual sorting and slow the package down. The label also carries the service details the carrier needs (the class of service, the weight used for rating) and the addresses. Treat it as a functional document, not a branding surface: cover it with clear tape and you can make the barcode unscannable, so use a proper label pouch or adhesive label instead.
The packing slip is a human-readable record. It lists what should be in the box so the recipient can check the order at a glance: item names, quantities, and the order number for reference. In a warehouse it doubles as the picking checklist: the packer works down the slip while filling the box. Small sellers sometimes skip it, but customers notice: a box with no slip feels anonymous, and when something is missing, the slip is what proves what was supposed to be there.
Because the slip is for the recipient, not the accountant. Many orders are gifts, and nobody wants the recipient opening a present to find what you paid. But there is a practical reason too: prices on a slip invite disputes ("I was charged more than this shows") and complicate partial refunds and replacements. The invoice, with prices, lives in the customer's email or account: the slip in the box stays a simple list of contents.
One exception: international shipments need a commercial invoice or customs declaration with values, and that is a separate document for customs officials, not the packing slip. Do not confuse the two: the customs form goes on the outside for border officers, the packing slip goes inside for the customer, and they serve completely different readers.
Each box gets its own shipping label: carriers track boxes, not orders, so a three-box shipment is three separate tracked items. For the packing slip, you have two good options. Put a copy of the full slip in every box, marked "Box 1 of 3," "Box 2 of 3," and so on, so the recipient can tell when the order is complete. Or put an itemized slip in each box listing only that box's contents, with a master slip in the first box. Either way, the recipient should never have to guess whether a missing item is in another box or was never sent.
If you are the one shipping, the label is the part you buy: describe the parcel to your AI assistant, approve the quoted price, and LetterAgent provides a Canada Post Xpresspost label PDF (Canada-only, flat rate, up to 5 kg). The packing slip is the part you print yourself from your store or order system. Keep the two jobs separate and both audiences happy.
Ready to ship it? Get a shipping label with LetterAgent: describe it to your AI assistant, approve the exact quoted price, and get your label.
LetterAgent is a working name. Prices include print, postage, and our service fee. US prices in USD, Canadian prices in CAD (Canadian prices exclude applicable sales tax, added at checkout). Currently in private testing.
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