Three codes, three jobs, and a lot of brands use the terms interchangeably until stock lands at a warehouse and something refuses to scan.
Here’s a quick overview of the three:
- A SKU is an internal code you create to identify your own products
- A barcode is the scannable symbol that carries a code
- A QR code is a two-dimensional barcode that carries far more data than a standard one.
A barcode can encode a SKU, but a SKU is not a barcode.
This guide covers what each identifier actually does, where each one sits in a fulfilment workflow, and how to work out which ones your business needs.
What a SKU actually is
SKU stands for stock keeping unit. It is an alphanumeric code that you create and control, and it exists purely for your own use. Nobody outside your business, other than a fulfilment partner working from your data, has any reason to recognise it.
Every sellable variant gets its own SKU. A t-shirt in three colours and four sizes is twelve SKUs, not one. That granularity is the point, because it lets you count stock, set reorder points, report on sales by variant, and pick the right item off the shelf. Bundled products work the same way, since a kitted item is assembled in advance and carries a SKU of its own.
A worked example. An organic navy t-shirt in a medium might be coded as TEE-ORG-NVY-M. The structure is yours to define, but what matters is that it stays consistent across the catalogue and that anyone in your business can read it without a lookup table.
That last point is where SKUs most often go wrong, and the cost of getting it wrong rises with every product you add. Our guide to SKU numbers covers how to build a convention that holds up as the catalogue grows, alongside the wider role SKUs play in stock control.
The thing to hold on to for the purposes of this comparison is simple. A SKU is information, not a symbol. It has to be printed and scanned before a warehouse can do anything with it, and that is where barcodes come in.
What a barcode actually is
A barcode is a symbol, not a number, it is the machine-readable representation of a code that already exists.
A standard one-dimensional barcode encodes a short string as parallel bars and spaces of varying width. A scanner reads the pattern and returns the underlying characters. The bars are the label, the number they encode is the identity.
That distinction matters, because different barcode types carry different numbers, and the number determines whether the code means anything outside your own systems.
- EAN-13 and UPC-12: Both are GTINs, or Global Trade Item Numbers, licensed through GS1. These are the retail-facing codes recognised globally. The same GTIN identifies the same product regardless of who is selling it.
- Code 128 and GS1-128: Used on cartons and shipping labels, where the code needs to carry more than a product identifier. Batch numbers, quantities, and pallet-level SSCC references travel this way.
- Internal barcodes: A barcode that simply encodes your own SKU string. Free to generate, useful inside your warehouse and your 3PL’s systems, and meaningless everywhere else.
The single most common misunderstanding in this area is worth stating plainly: a barcode can encode a SKU or a GTIN. Which one it carries decides whether the code works only in your four walls or across the whole of retail.
What a QR code actually is
QR stands for Quick Response and is a two-dimensional matrix barcode, so it is technically a type of barcode, but it behaves very differently from the striped label on a shop shelf.
The difference that matters most is data capacity. A one-dimensional barcode holds a short identifier, typically somewhere in the region of 8 to 25 characters depending on the symbology. A QR code can hold thousands. That opens up URLs, batch and lot data, expiry dates, and individual serial numbers.
Two other properties are worth knowing:
- Error correction is built in. A QR code can still be read when part of it is dirty, scuffed, or torn. In a warehouse, where labels take a beating, that is a practical advantage over a 1D barcode, which needs its bars intact.
- A phone can read it. No dedicated hardware required, which is what makes QR codes viable on consumer packaging as well as inside operations.
There is also a conceptual difference. A retail barcode identifies a product line. A QR code can identify an individual unit, which is what makes item-level traceability possible.
Worth watching: GS1 is working toward two-dimensional codes at point of sale, which would let a single code carry both the GTIN a till needs and a web link a customer can scan. Roll out across the UK is planned for late 2027.
SKU vs barcode vs QR code side by side
| SKU | Barcode (1D) | QR code (2D) | |
| What it is | An internal code | A scannable symbol carrying a code | A scannable matrix carrying a code |
| Who creates it | You do | You do, or GS1 issues the number | You do |
| Format | Alphanumeric, typically 8 to 12 characters | Parallel lines encoding a short string | Matrix encoding thousands of characters |
| Recognised by | Your systems and your fulfilment partner | Your systems, retailers, marketplaces, couriers | Any smartphone, plus 2D-capable scanners |
| Cost | Nothing | Nothing for internal codes, licence fee for GS1 GTINs | Nothing |
| Best used for | Internal stock control and reporting | Fast, reliable scanning at pick, pack, and till | Item-level data, traceability, consumer-facing links |
| Can it be changed | Yes | A GTIN cannot, once assigned | Static codes no, dynamic codes yes |
The comparison framing is a little misleading, though, because these three are not really competing with each other. Most brands need all of them, doing different jobs at different points in the chain. The useful question is not which one wins, iIt is which one is doing the work at each stage.
Where each identifier sits in a fulfilment workflow
Walking a product through a warehouse makes the roles much clearer.
Goods-in
Stock arrives at carton or pallet level. The team scans the carton label, which is usually a GS1-128 carrying quantity and reference data, and checks it against the purchase order. Whatever is on that carton then gets mapped to your SKU inside the warehouse management system. If your SKUs are duplicated, inconsistent, or missing, this is the stage where it shows up.
Putaway
Racking locations and bin fronts carry their own barcodes. These have nothing to do with the product and everything to do with knowing where it went.
Picking
A picker scans the location, then scans the item. That item scan is almost always a 1D barcode, encoding either your SKU or the product’s GTIN. Speed and reliability matter far more than data richness here, and that is precisely why one-dimensional barcodes still dominate the pick face.
Packing
The picked items are scanned again and verified against the order. This is the step that catches a mispick before it becomes a return, and it only works if every unit carries a scannable code.
Dispatch
The courier label is a barcode too, generated by the carrier and carrying the tracking number. It is not your SKU and not your GTIN.
Set out like that, the conclusion about QR codes is that they have very little to do at the pick face. Their value sits elsewhere: on the packaging, on the insert, and on the outer carton, where the extra data capacity actually earns its keep.
It is also why an eCommerce fulfilment partner will ask for a clean, scannable SKU for every variant during onboarding. Teams at third-party logistics providers like Green Fulfilment see the same issue repeatedly: duplicate or mismatched SKUs are among the most common causes of delay when stock first arrives, and they are far cheaper to fix before a pallet is on the dock than after.
Do you need barcodes if you only sell direct to consumer?
If you sell only through your own store and fulfil from a single location, internal SKU barcodes are enough. There is no need to license GTINs for products nobody else is selling.
That changes as soon as you:
- List on Amazon, eBay, or most other online marketplaces
- Sell into physical retail or through wholesale distribution
- Expand internationally, where regulated product codes are commonly required for market entry
When you do need them, buy GTINs directly from GS1. Codes bought from resellers may be recycled, already assigned, or unresolvable against your business, and the saving is not worth a suppressed listing.
One piece of forward planning is worth doing at the same time. GS1 prefixes are issued with a set capacity, so it pays to estimate how many codes you will need over the next few years rather than the next few months. Exhausting a prefix means starting a new one rather than extending the one you have.
When QR codes are worth adding
QR code vendors have a habit of overstating this, so it is worth being even-handed. QR codes solve specific problems very well and add cost and complexity where those problems do not exist.
They are worth adding when:
- You need serialised, item-level traceability, tracking batch, lot, or individual unit rather than product line
- Product information will not fit on the packaging and needs somewhere to live
- Compliance or safety information has to travel with the product itself
- You want a digital destination on-pack that can be updated without reprinting
That last point depends on the type of code. A static QR code is fixed at the moment it is created. A dynamic QR code stores a redirect, so the destination can be changed and scans can be tracked after the label is printed.
They are not worth adding when the job is simply to identify a product line at the till or on the pick face. A 1D barcode does that faster, with cheaper hardware, and with fewer things to go wrong.
There is a compliance angle for brands selling into the EU. The General Product Safety Regulation, EU 2023/988, brings labelling expectations alongside the requirement for an EU-based Responsible Person, and digital labelling is one of the mechanisms brands are using to carry that information on-pack. If EU expansion is on your roadmap, it is worth understanding how those requirements interact with EU fulfilment before you commit to a packaging run.
Getting product identification right before you scale
Three things are worth doing early, because all of them get harder as the catalogue grows.
Build a clean SKU convention now, while your product range is small enough to reorganise in an afternoon. Licence GTINs from GS1 before you need them, rather than in the week a marketplace listing is due to go live. Treat QR codes as an addition to your identifier stack rather than a replacement for what is already working.
Product identification is the layer everything else sits on. Accurate picking, real-time stock counts, clean sales reporting, and reliable dispatch all depend on the codes being right at the moment stock arrives in the warehouse. Get that layer wrong and every system built on top of it inherits the problem.
Frequently asked questions
Are a SKU and a barcode the same thing?
No. A SKU is a code you create to identify a product internally. A barcode is a scannable symbol that can carry that code, or carry a different one such as a GTIN. The SKU is the information. The barcode is the delivery method.
What is an example of a SKU?
A SKU for a medium navy organic t-shirt might be TEE-ORG-NVY-M. The structure is yours to define, but it should stay consistent across the catalogue and be readable by anyone in the business without a lookup table.
Is a barcode a SKU or a GTIN?
It can be either. A retail barcode almost always encodes a GTIN, which is licensed through GS1 and recognised globally. An internal warehouse barcode usually encodes your own SKU and carries no meaning outside your systems.
Are QR codes replacing barcodes in warehouses?
Not at the pick face. One-dimensional barcodes are faster to scan with dedicated hardware and carry everything a picker needs. QR codes are being added where item-level data, traceability, or a consumer-facing link is required, rather than replacing 1D codes across the board.
Do I need to buy barcodes to sell on Amazon?
In most cases yes. Amazon and other major marketplaces generally require a GTIN, which you licence through GS1.
Can one product have a SKU, a barcode, and a QR code?
Yes, and most do. The SKU handles internal stock control, the retail barcode handles the till and the marketplace, and a QR code, where present, carries additional data such as traceability information or a link to product details.
