What is a shipping label? Anatomy, barcodes and printing

A shipping label is a printed or digital document attached to a parcel or pallet that tells everyone in the delivery chain what to do with it. It carries the sender, the receiver, the chosen transport service, handling instructions, and the barcodes that let carriers, warehouses and sorting hubs move the shipment automatically and track it at every step.

For anyone running shipping operations, the label is also where most of the small, expensive mistakes happen, and where most of them can be designed out. Warehouse teams that get labeling right ship faster, missort less, and answer fewer support tickets.

What is a shipping label?

A shipping label, sometimes called a parcel label or transport label, is the identity document of a logistics unit. A logistics unit can be a single parcel or a pallet holding many parcels; either way, it carries one primary carrier label with one unique ID. A shipment can carry other labels alongside it (dangerous goods marks, customs paperwork, internal warehouse labels), and the carrier label is the one the delivery chain runs on. It exists so that any party who touches the shipment (the warehouse packer, the driver, the sorting machine, the delivery courier, the receiver) can read what it is, where it is going, and how it should be handled, without asking anyone.

Every carrier requires one in some form. A parcel without valid shipping data is, operationally speaking, invisible: it cannot be booked, sorted, tracked or delivered through any automated process. Where the label is printed can vary. Some services print it at a drop-off point, while others use a QR code the customer shows on a phone. The identifier and shipping information behind it still have to exist.

A shipping label and a packing slip do different jobs. The label sits on the outside of the parcel and directs the carrier. The packing slip describes the order contents for the receiver and travels with or inside the parcel. They can be combined into a single printed document, one of the printing efficiencies covered later in this guide.

What information is on a shipping label?

The human-readable part of a shipping label carries a consistent core, whatever the carrier:

• Sender name and address, so the parcel can be returned if delivery fails.
• Receiver name and address, the destination that everything else serves.
• Information for the carrier and driver, such as the terminal, route or distribution area codes the carrier uses internally.
• The chosen transport service, for example standard home delivery, express, or delivery to a pickup point.
• Weight and volume, which drive pricing, vehicle planning and handling.
• Specific transport instructions where they apply, such as cash on delivery, insurance, or notification preferences.

All of that is printed for people. The label's second job is machine work, and that is where the barcodes come in.

What does a shipping label look like? The barcode layers

Look closely at a label from any major carrier and the same split appears: text for people, barcodes for machines. The exact layout and placement vary by carrier, and different barcodes can serve different jobs.

Routing barcodes encode sorting information. When a parcel passes through a large hub, automated sorters scan these codes and physically direct the parcel to the right chute, dock or vehicle. No person reads the address; the machine reads the routing code.

The parcel ID barcode is the most important element on the label. It is the shipment's unique identifier, and it is what makes tracking possible for every party in the supply chain. Carrier systems record each scan of that ID (departure, arrival at a hub, out for delivery, delivered, exception) as a tracking event. For most shipments this is also the tracking number the receiver sees, though naming and the exact identifier model vary by carrier. The parcel ID links the physical shipment to its digital tracking record.

A smudged barcode can stop a perfectly addressed parcel.

If the machine-readable layer fails, the shipment drops out of automation and into manual handling, which is slower and more error-prone. The printed address is still there, but automated sorting systems are built to read the barcode.

Shipping label standards: GS1, SSCC and GS1-128

Much of global logistics labeling follows standards maintained by GS1, the organization behind the barcode on almost every retail product. For logistics units, the key elements are:

• The SSCC (Serial Shipping Container Code), an 18-digit number that uniquely identifies one logistics unit. It is built from an extension digit, a GS1 company prefix, a serial reference and a check digit.
• The GS1-128 barcode, the barcode format that carries the SSCC (application identifier 00 always means an SSCC).
• The GS1 logistics label layout, which arranges the label in three sections: a free zone at the top for company information, a middle section with human-readable data, and a lower section with the barcodes.

The SSCC also links the physical parcel or pallet to electronic messages about it, such as the advance shipment notification a retailer's warehouse receives before the truck arrives. Scan the SSCC on arrival and the receiving system already knows what is inside, which is the foundation of automated receiving and the reason large retailers routinely make SSCC labeling a condition of supplying their distribution centers. Many carriers use global and regional standards like these, but carrier-specific requirements still vary.

Why every carrier's label is different

The carrier decides what goes on the label: layout, barcode type, required fields, terminal codes and service markings. GS1 provides common standards, but each carrier's label remains its own specification, and carriers update those specifications as their networks change.

With one carrier, this is easy. Implement the specification once, print, done. The work compounds with each carrier you add. A retailer shipping with eight carriers across three countries maintains a separate label specification and booking format for each, with updates arriving on eight different schedules. Carriers change label layouts, barcode requirements and data fields as their networks and sorting technology evolve, turning labeling from a one-time implementation into ongoing maintenance. A single carrier brand can also operate separate divisions with different systems and label requirements, so "we ship with DSV" can mean several technical integrations depending on the division, country and direction of travel. Clean integrations start by naming the exact carrier service rather than the carrier brand, so nobody builds against the wrong division.

nShift maintains label specifications and booking integrations for a carrier network of more than 1,000 carriers across 190+ countries, and keeps them current as carrier requirements change. Your systems connect once; the label that comes out matches whichever carrier you booked.

How do shipping labels work in practice?

The label sits in the middle of a chain that starts long before printing and ends long after:

1. An order is confirmed. In ecommerce this often starts at checkout, where the shopper picks a delivery option drawn from the carriers you offer.
2. The shipment is booked. Your warehouse or ERP system sends the shipment data to the chosen carrier: addresses, weights, service, references.
3. The label is generated and printed. The carrier's specification determines the layout and barcodes; the label is applied to the parcel or pallet.
4. Machines take over. Routing barcodes steer the parcel through sorting; each scan of the parcel ID becomes a tracking event your team and your customer can see.
5. Delivery, and sometimes return. The same identification logic runs the journey back if the receiver returns the goods.

Where the label gets created depends on the setup: directly in a carrier's portal for occasional shipments, inside an ecommerce platform or marketplace, or through shipping software and APIs once volumes make manual booking impractical. The process is the same; the level of automation changes.

Each scan updates the digital shipment record. Tools like nShift Track turn parcel ID scans into standardized tracking events across carriers, so a shipment booked with any carrier reports its progress in one place, in one format.

Depending on the shipment, the shipping label may be accompanied by waybills and customs documents such as CN22 and CN23 declarations for cross-border parcels. A waybill is the transport document, the record of the shipment and its terms, while the label is the physical identifier on the unit itself. Carriers vary in how they use the terms, so it helps to pin down the vocabulary early in an integration. Delivery management software collects this data once and forwards what each carrier needs; customs clearance itself stays with the carrier or broker. For dangerous goods, the shipper remains legally responsible for accurate data and correct labeling, while the software passes that information to the carrier within the transport process.

Where shipping labels are heading

Shipping label technology is mature, but the workflows around it continue to change.

Volumes keep rising. Ofcom measured 4.2 billion parcels in the UK in the 2024-25 financial year, up 7% year on year and above the pandemic peak. Each of those parcels needed an identifier a carrier could scan. Growth at that scale rewards operations that print correctly the first time, because the cost of manual exceptions rises with volume.

Automation raises the stakes on print quality. As hubs and warehouses push more volume through automated sorters, the machine-readable layer of the label does more of the work. An unscannable barcode used to slow a parcel down; increasingly it kicks the parcel out of the automated flow entirely.

The consumer's printer is leaving the process. Carriers now offer QR-code flows where the customer shows a code at a service point and the label is printed there, or skipped entirely. This is well established in returns, where label-less returns remove the customer's printer from the process; some carriers extend the same idea to outbound shipments, such as QR-code return shipments available with Bring in Norway. As customer-facing paper disappears, more shipment data moves directly between systems.

Printing shipping labels at scale

At hundreds or thousands of parcels a day, label printing directly affects warehouse throughput.

DTK, a logistics provider shipping across six European countries with nShift Ship, cut the time required to ship from two and a half minutes to 15 seconds per shipment, a 90% reduction that amounts to 35 printing hours saved every day. Part of that came from reducing the number of labels per parcel from two to one, by combining the packing slip and shipping label. GLOWiD, a Scandinavian retailer, took a different route: after moving to automatic printing through nShift, order processing fell from three minutes to 30 seconds per shipment and error rates dropped by up to 50%, including mistakes in shipping selection and label printing.

Both results rest on the same capabilities you should expect from multi-carrier shipping software:

• One integration, every carrier's label. The software holds each carrier's specification and generates the correct label as carriers are added.
• Automatic printing in the packing flow. The label prints as part of processing the order, with no separate manual step where a wrong-label error can enter.
• Volume tooling. Mass printing for identical shipments to many receivers, fast reprints, and print via user interface or API depending on how your warehouse works.
• Document consolidation. Merging the transport label with delivery notes or invoices into a single document, which is how a parcel goes out with one label instead of two.
• Room for your brand within the carrier's rules. Adding a logo or a QR code as an overlay on the carrier label, without breaking the specification.

The printing layer itself

High-volume label printing depends on format and print routing.

Labels are generated either as PDF documents, which any office printer can handle, or in native thermal-printer languages such as ZPL, which dedicated label printers consume directly onto the 4 x 6 inch (roughly A6) label stock most parcel networks use. Thermal printing is the default in busy warehouses: no ink, no toner, faster output, and adhesive label stock instead of paper and pouches. A shipping platform should produce whichever format your hardware expects, per printer, per station.

At a packing station, the label should appear as soon as the order is processed, without anyone opening a dialog box. That requires print software that runs as a service, takes jobs via the user interface or API, and routes each job to the right physical printer, whether the trigger came from a warehouse scanner, an ERP workflow or a webshop backend. When a label misprints, a reprint should be one action from the shipment record, without rebooking anything. Reliable print routing is basic warehouse infrastructure, and high throughput depends on it.

nShift Ship provides these capabilities on top of the full carrier network, from label generation and mass printing through customs documentation. On the warehouse floor that means every parcel gets the right label for the right carrier the first time, whatever the day's order volume.

See how nShift can take carrier-by-carrier label maintenance out of your workflow. Book a demo and bring your carrier list.