The short answer
A SKU, GTIN, batch number, and serial number answer different questions:
- A SKU is usually an internal stock or catalogue code.
- A GTIN identifies a defined trade item or product variant in the GS1 system.
- A batch or lot number identifies a production or supply batch.
- A serial number identifies one individual instance of a product.
For a Digital Product Passport, the legally relevant concept is the persistent unique product identifier connected to the data carrier. The applicable product-group delegated act decides whether the DPP refers to the model, batch, or item. (ESPR, Articles 9 and 10)
For a serialised item, a common GS1 pattern is GTIN plus serial number. The GTIN identifies the base product, while the serial identifies the individual instance. For a batch-level record, the pattern is commonly GTIN plus batch or lot number. GS1 Digital Link can express these identifiers in a URI that works both as a machine-readable identifier and as a web connection. (GS1 Digital Link Quick Start Guide)
Identifier terms at a glance
| Term | Full name or common meaning | Scope | Usually assigned by | Identifies one physical item? | DPP relevance |
|---|---|---|---|---|---|
| SKU | Stock keeping unit | Internal catalogue or inventory scope | Manufacturer, retailer, or operator | Not necessarily | Useful for mapping systems, but not automatically the legal DPP identifier |
| GTIN | Global Trade Item Number | A defined trade item, model, or variant | GS1 member company under GS1 rules | No, by itself | Often the base product identifier in a GS1 Digital Link |
| Batch or lot | Production or supply batch code | A group made or handled together | Manufacturer or supply-chain operator | No | Can identify a batch-level DPP when the applicable act requires it |
| Serial number | Individual instance number | One unit within a product identity | Manufacturer or responsible operator | Yes, when used with the relevant base identifier | Supports item-level identity and individual lifecycle traceability |
| Unique product identifier | Legal or technical identifier that persistently identifies the relevant product scope | Model, batch, or item, depending on the rule | As required by the applicable framework and standards | Depends on the required level | The DPP must connect to this identifier through a data carrier |
The key mistake is treating "unique" as a synonym for "serial number." A GTIN is unique to a defined product, but it can be printed on many units of that product. GS1 explains that one GTIN can be used unlimited times on the same product. A serial number adds the individual-instance distinction. (GS1, How GTINs and barcodes work)
SKU vs serial number
What a SKU does
A SKU is an internal business identifier. It may represent a product family, a size and colour combination, a battery model, a sales configuration, or an inventory variant. Two companies can assign different SKUs to the same commercial item, and one company can change its SKU without changing the physical product's identity.
A SKU is therefore valuable for ERP, PIM, warehouse, and commerce workflows, but it is not automatically persistent, interoperable, or globally unique. Do not assume that a SKU alone satisfies a DPP's unique product identifier requirement.
What a serial number does
A serial number is assigned to an individual instance for its lifetime. GS1 describes serialization as the process of generating and applying codes or serial numbers that uniquely identify each individual instance. An individual trade item can be identified by combining its GTIN with its serial number. (GS1, Serialization and unique identification)
For DPP operations, that difference affects recalls, repairs, warranty events, refurbishment, ownership or custody changes, and other events that apply to one unit rather than to every unit of a model.
GTIN vs serial number
Think of the pair as what it is plus which one it is:
- GTIN: "This is the defined product or variant."
- Serial number: "This is the specific unit of that product."
GS1's Digital Link guidance uses the GTIN as the primary key and permits it to be qualified by a batch or serial number. In the URI examples, a GTIN alone represents the product, while GTIN plus serial identifies an individual item. (GS1 Digital Link Quick Start Guide)
Illustrative examples below use fictional values and are not assigned identifiers:
| Business meaning | Illustrative identity | What it can distinguish |
|---|---|---|
| Product variant | GTIN 09524000059109 | The defined trade item or variant |
| Batch | GTIN 09524000059109 + LOT ABC7 | The product made or handled in lot ABC7 |
| Individual item | GTIN 09524000059109 + SERIAL 004812 | One physical unit within the product variant |
Do not copy these values into production. Use your own identifiers and validate them under the relevant issuing and data-carrier rules.
Batch number vs serial number
A batch number groups products that share a production or supply context. It is useful when a property applies to every unit in the group, such as a manufacturing run, material lot, supplier declaration, or quality event.
A serial number separates one unit from all other units in that batch. It is necessary when the record must capture unit-level status or history, or when a legal rule requires an item-level DPP.
| Question | Batch answer | Serial answer |
|---|---|---|
| How many units does it cover? | A defined group | One unit |
| Can the same value appear on several products? | Yes, within the batch | No, not for two units under the same base identity |
| Typical data | Production date, plant, supplier lot, common quality result | Unit commissioning, repairs, state, ownership or lifecycle event |
| Main benefit | Efficient group traceability | Individual traceability |
| Main risk | Hides differences inside the batch | Higher issuance, labelling, and data-management effort |
Neither level is automatically "better." The correct level is the level required by the applicable delegated act and supported by the product's real data and lifecycle.
What the ESPR says about DPP identifiers
The ESPR provides a framework rather than one universal identifier recipe for every product. Article 9(2) says product-group delegated acts specify, among other things, the data carrier and whether the DPP is established at model, batch, or item level. Article 10 requires the DPP to be connected through a data carrier to a persistent unique product identifier, and says the data must refer to the model, batch, or item as specified by the delegated act. (ESPR, Articles 9 and 10)
That has three implementation consequences:
- Do not choose identifier granularity from a software screen alone.
- Keep the identifier layer separate from descriptive product data.
- Make the model, batch, and item relationships explicit so a future delegated act can be implemented without rebuilding the catalogue.
The battery passport uses model and individual-battery data
Batteries provide the clearest current example. From 18 February 2027, Article 77 of the Battery Regulation requires every LMT battery, industrial battery above 2 kWh, and electric vehicle battery placed on the EU market or put into service to have a battery passport.
Article 77 requires the passport to contain information relating to the battery model and information specific to the individual battery, including information resulting from use. It also requires the passport to be accessible through a QR code that links to a unique identifier attributed to the battery. (Battery Regulation, Article 77)
For a battery manufacturer, the practical identifier stack is therefore:
| Layer | Example role in the battery passport |
|---|---|
| Internal SKU or model code | Connects ERP, PIM, engineering, and production systems |
| Model identifier or GTIN where used | Identifies the defined battery model or trade item |
| Batch or lot | Connects units to a manufacturing context where required |
| Individual unique identifier or serialised identity | Distinguishes the physical battery and its individual data |
| QR data carrier | Provides the scan path to the identifier and passport |
The regulation also requires accurate, complete, and up-to-date information. If a battery is prepared for reuse, repurposed, or remanufactured, the new battery passport must be linked to the original passport or passports. (Battery Regulation, Article 77(4) and (7))
How GS1 Digital Link connects an identifier to online information
A GS1 Digital Link URI can carry the identifier hierarchy in a web-compatible structure. GS1's quick-start guidance explains that the QR code has two functions:
- It identifies a product using recognised GS1 identifiers.
- It provides a web connection that can be handled like a URL by a phone or other software.
The guidance identifies 01 as the application identifier for GTIN, 10 for batch or lot, and 21 for serial number. When a batch or serial number is used, it is combined with a GTIN. (GS1 Digital Link Quick Start Guide)
Conceptually:
Product level: GTIN
Batch level: GTIN + batch/lot
Item level: GTIN + serial number
The exact DPP resolver, domain, path, and access model depend on the implementation. A URI is not the same thing as the passport database. It is an identifier and connection mechanism that must resolve to the appropriate information under the product's access rules.
Identifier design checklist
Before you generate DPPs or print QR codes, answer these questions:
- What legal instrument applies to this product group?
- Does the applicable act require model, batch, or item-level data?
- Which internal fields are SKUs, and which are persistent external identifiers?
- Does every item have a stable serial or unique identifier where item-level data is required?
- How are GTIN, batch, serial, SKU, and passport IDs mapped without ambiguity?
- Can a scan resolve to the correct version of the passport?
- How are duplicate, retired, replaced, or corrected identifiers handled?
- How are lifecycle events linked to the item that experienced them?
- How will packaging and documentation carry the data carrier when product marking is not feasible?
- Can the data be exported and audited independently of the application that stores it?
The most important control is an authoritative crosswalk. Maintain one record that shows which internal SKU, model identity, batch, serial, and DPP identifier belong together. Treat changes to that mapping as controlled data changes, not as casual spreadsheet edits.
Common mistakes to avoid
Treating a SKU as a serial number
A SKU can cover thousands of units. It is useful for stock and catalogue management, but it does not distinguish one physical unit.
Printing a GTIN-only QR code for an item-level obligation
A GTIN-only code identifies the product variant, not the individual unit. If item-level identity is required, the carrier must resolve through an identifier that includes or maps to the individual identity.
Using a batch code where unit history matters
A batch can show that a unit came from a production lot, but it cannot by itself show which single unit was repaired, repurposed, recalled, or updated.
Assuming every product group follows the battery model
Battery rules are specific. Other DPP obligations may use model or batch level. Confirm the delegated act before committing to an item-level QR print run.
Making the QR code the system of record
A QR code is a carrier. The authoritative record is the passport data and its identifier mapping. Plan for versioning, access control, corrections, and long-term availability.
Conclusion
The identifier question becomes simple when each term keeps its proper role. A SKU helps your internal systems find a product. A GTIN identifies a defined trade item. A batch number groups units. A serial number distinguishes one physical unit. A DPP identifier connects the legally required level to a data carrier and a persistent record.
For ESPR products, the delegated act decides whether the DPP is model, batch, or item level. For covered batteries, the Battery Regulation already requires model information plus individual-battery information and a QR-linked unique identifier from 18 February 2027. Build your identifier architecture around those distinctions now, before printing, integration, and supplier workflows make the wrong mapping expensive to unwind.
Continue through the cluster
Next, apply the hierarchy to the one DPP per product decision, the battery QR-code rule, the battery model-to-item data architecture, or the operational guide to creating thousands of DPPs and unique QR codes.
