Using Barcodes for Inventory Management: A Practical Guide for UK Sellers

Barcode Formats Explained

Not all barcodes are the same. Different formats encode different types of data and are used in different contexts. Understanding which format to use for which purpose removes a lot of confusion when setting up a barcode system.

For most UK sellers, you will primarily work with two formats: EAN-13for product identification (the barcode printed on the product packaging by the manufacturer, or purchased from GS1 for your own products) and Code 128for internal labels you generate yourself — bin locations, SKU labels, picking sheets.

Why Barcodes Matter for Inventory Accuracy

The fundamental problem barcodes solve is human error in data entry. When a member of staff manually types a SKU or product name to log stock movement, mistakes happen. A typo in a SKU increments the wrong product. A misread digit when logging goods-in gives you a wrong quantity. Over days and weeks, these small errors compound into a stock count that gradually diverges from physical reality — and you will not notice until you do a stocktake and discover the discrepancy.

A scanner eliminates this class of error entirely. The scanner reads the barcode optically and sends an exact string to the software. There is no transcription step, no handwriting to interpret, no number to misremember. Studies of warehouse operations consistently show that scanning reduces picking errors by 60–80% compared to manual paper-based processes.

Speed is the second benefit. An experienced picker with a scanner can process a simple order line in 3–5 seconds. The equivalent manual process — read the order, find the product, confirm the SKU by eye, log the pick — takes 15–30 seconds. At 50 orders per day, that difference is significant. At 200 orders per day, it is transformative.

How Barcodes Work in Practice

A barcode system has three components: the barcode itself (printed on a label or packaging), a scanner to read it, and software to act on the data. The scanner reads the barcode and sends the encoded string (typically a number or alphanumeric code) to the software via USB, Bluetooth, or Wi-Fi. The software looks up that code in its database and identifies the matching product, then performs whatever action is appropriate for the workflow — incrementing stock, decrementing stock, confirming a pick, triggering a reorder alert.

Most handheld barcode scanners emulate a keyboard. When you scan a barcode, the scanner “types” the barcode number into whatever field is active on screen — exactly as if you had typed it manually, but instantly and without error. This means any software that accepts text input can work with a barcode scanner with zero configuration. More sophisticated integrations use dedicated scanning modes where the software listens for scanner input and routes it to the right workflow automatically.

Setting Up a Barcode System from Scratch

Setting up barcoding for the first time does not need to be a large project. Here is a practical sequence for a small UK seller:

• Audit your product catalogue. For each SKU, check whether it already has an EAN barcode on the packaging. Most branded products from UK wholesalers will. Note which products do not have barcodes and need labels created.
• Create or obtain barcodes for unlabelled products. For products you have manufactured or private-labelled, you need to register EAN codes through GS1 UK. For internal-use labels only, generate Code 128 barcodes from your own SKU codes using a free generator.
• Set up your label printer and print labels. Label products that do not have printed barcodes. Also print bin location labels for your warehouse shelves.
• Configure your inventory software. Map each barcode to the correct SKU in your inventory system. In Salync, this is done in the product record — enter the EAN code and the system will match scans to that product.
• Connect your scanner and test. Pair a Bluetooth scanner or plug in a USB scanner. Test scanning a few products to confirm they resolve to the correct SKU in your system.
• Roll out to your workflows. Start with goods-in, then pick/pack, then stocktakes. Introduce one workflow at a time so your team can build confidence before moving to the next.

Assigning Barcodes to Products That Do Not Have One

This is one of the most common practical challenges for UK sellers. You have a product — perhaps something sourced from a smaller supplier, or a private-label item you have had manufactured — and there is no barcode on the packaging.

Internal-use labels

If you only need barcodes for your own warehouse use — goods-in, picking, stocktakes — you can create Code 128 labels based on your own internal SKU codes. Free barcode generators (search “free Code 128 barcode generator”) let you enter any text string and generate a printable barcode. Print this on a label and apply it to your products. These barcodes are unique to you — they are not registered anywhere, which is fine for internal use but means they will not match any marketplace catalogue.

EAN codes for marketplace listings

If you need to list on Amazon or eBay with a barcode that matches their catalogue, you need a genuine registered EAN-13 code. GS1 UKis the authoritative source. Membership starts at around £107 per year (as of 2025) and gives you access to a range of unique EAN codes registered in your company's name. Once you have an EAN, you assign it to a specific product variant and use it consistently across all your listings.

Do not buy “cheap EAN codes” from third-party sellers. Amazon in particular runs checks against the GS1 database and will flag or suppress listings where the EAN is not registered to the brand claiming it. This can result in listing removal and account warnings that are difficult to resolve.

Barcode Labels and Label Printers

For applying barcodes to unlabelled products, you need a label printer. There are two main types used in small warehouse environments:

Thermal transfer label printers

Thermal transfer printers use a ribbon to print onto label stock. They produce durable, high-quality labels that resist smearing and fading. Dymo LabelWriter and Zebra desktop printers are popular options in this category. Labels produced by thermal transfer are more durable than direct thermal and are a better choice for products that will be stored for months or exposed to varying temperatures.

Direct thermal label printers

Direct thermal printers use heat-sensitive paper — no ribbon required. They are cheaper to run and simpler to maintain. The trade-off is that labels fade over time, especially in warm or bright environments. For short-lifecycle stock or labels that will be scanned within a few weeks of printing, direct thermal works well. For longer-term warehouse labels or bin location signs, thermal transfer is more reliable.

Recommended label formats for inventory use include 50mm × 25mm for product labels (enough space for a readable Code 128 or EAN-13, the SKU number, and a product description) and 100mm × 50mm for bin location labels that need to be visible from a distance.

Barcode Scanners for Small Warehouses

The scanner is the most visible part of a barcode system, and there is a wide range of options across price points.

USB wired scanners

The simplest and most affordable option. A USB scanner plugs into a computer or laptop and works immediately — no drivers, no pairing. Good for fixed packing stations where the operator is always close to a PC. Suitable entry-level options cost £25–£50. The limitation is the cable — it restricts movement, which matters for goods-in or stocktake workflows where you need to move around the warehouse.

Bluetooth wireless scanners

Bluetooth scanners pair with a computer or tablet and allow free movement within approximately 10 metres. Excellent for picking workflows where the operator moves between shelves. A good Bluetooth scanner costs £60–£150. Look for models with a USB charge cradle so the scanner is always charged and parked in a consistent location between uses.

Mobile computers / Android terminals

For larger operations, purpose-built Android mobile computers (from Zebra, Honeywell, or Datalogic) combine a rugged barcode scanner with a touchscreen running a warehouse management app. These are significantly more expensive (£300–£800+) but offer much more capability — the operator can see the full picking list, confirm quantities, and handle exceptions on the device without returning to a fixed terminal. Most small sellers do not need this tier of equipment, but it becomes relevant at volumes of 100+ orders per day.

Smartphone scanning

Modern smartphones scan barcodes well enough for occasional use. Many inventory apps offer a built-in camera scanning mode. For a small seller doing a monthly stocktake or checking in a small delivery, a phone is perfectly adequate. For daily high-volume picking, the ergonomics are poor compared to a dedicated scanner — scanning is slower, holding a phone in one hand while picking with the other is awkward, and the screen is a fragile liability in a warehouse environment.

Scanning at Goods-In (Receiving Stock)

Goods-in is one of the highest-value points in your barcode workflow. When stock arrives, scanning each product against the purchase order gives you a verified, accurate count of what actually arrived — rather than trusting the supplier's packing note, which may not always match the physical delivery.

A good goods-in workflow looks like this: the operator opens the relevant purchase order on the inventory screen. As each product is unpacked, they scan the barcode. The system matches the scan to a line on the PO and increments the received count. Any discrepancy between the PO quantity and the scanned count is flagged immediately. When the delivery is complete, the system updates stock levels and closes the PO (or marks it as partially fulfilled if items were missing).

This process is much faster and more accurate than manually counting boxes and ticking off a paper delivery note. It also creates an automatic audit trail — you can prove exactly what arrived and when, which is useful if a supplier later disputes a short delivery claim.

Scanning at Pick/Pack (Dispatch)

Scanning at the pick/pack stage serves two purposes: confirming that the correct product is being packed for each order, and decrementing stock accurately as items leave the warehouse.

A scan-to-confirm workflow works like this: the picker pulls the order details up on screen. They pick the item from the shelf and scan it before placing it in the box. The system confirms it matches the order line — green tick, proceed. If the scan does not match — because the wrong item was picked — the system flags an error before the item is packed and shipped. This single check prevents wrong-item dispatch errors, which are one of the most common causes of negative feedback and “item not as described” returns in ecommerce.

At the same time, the system decrements the stock count for the scanned SKU. The deduction happens at the moment of confirmed pack rather than when the order is created, which gives you a real-time view of exactly what stock remains available as orders are fulfilled throughout the day.

Doing a Stocktake with a Scanner

A barcode scanner transforms a stocktake from a tedious manual process into a fast, reliable exercise. Instead of counting products by hand and recording numbers on a paper sheet, the operator moves through the warehouse scanning each product. Each scan increments the count for that SKU in the stocktake session. At the end, the system compares the scanned counts against the expected stock levels and shows any discrepancies.

The efficiency gain is substantial. A stocktake that takes a day to complete with pen and paper can often be done in 2–3 hours with a scanner. The accuracy is also significantly better — the scanner confirms the exact SKU being counted, whereas manual counting relies on staff correctly identifying products that may look similar.

For a rolling stocktake approach — where you count a subset of your SKUs each week rather than counting everything at once — scanning makes this practical at any business size. Count 20% of your SKUs per week and you have done a complete cycle count every 5 weeks without shutting down operations for a full stocktake day. See our full guide on how to do a stocktake for more detail on planning and running the process.

Barcodes Across Channels: eBay and Amazon Requirements

Beyond your internal warehouse use, barcodes play an important role in how your products are listed and found on the major UK marketplaces.

eBay and EAN codes

eBay uses EAN codes (and other product identifiers like ISBN for books and MPN for parts) to match your listings to its product catalogue. When you provide an accurate EAN, eBay populates many of the item specifics automatically from catalogue data, which improves listing visibility and reduces the risk of incorrect information. For many categories, eBay actively requires an EAN — you will see warnings or your listing may be suppressed if you leave the EAN field blank for a branded product.

If your product does not have an EAN — for example, handmade items or truly unique products with no manufacturer barcode — eBay provides an exemption option. You can select “Does not apply” in the identifier field rather than inventing a barcode.

Amazon and GTINs

Amazon requires a GTIN (Global Trade Item Number — an umbrella term that includes EAN-13, UPC-A, and ISBN) for most product listings. Amazon validates GTINs against the GS1 database. If the GTIN you provide does not match the brand name you have entered, Amazon will reject the listing or add a suppression. This is why buying cheap bulk EAN codes from unauthorised sources is problematic — they fail Amazon's verification checks.

For products where no GTIN exists (genuine private-label products where you own the brand), Amazon offers a GTIN exemption process. You apply for an exemption for your specific brand and product category, which allows you to list without a barcode. Amazon Brand Registry is the more permanent solution — registering your brand with Amazon gives you greater control over your listings and product pages.

For FBA sellers, Amazon assigns an FNSKU (Fulfillment Network Stock Keeping Unit) barcode to each product you send to FBA. You must print and apply FNSKU labels to every unit before sending to the fulfilment centre, unless Amazon's commingling programme is used (which means your inventory is mixed with other sellers' units of the same EAN — generally not recommended for anything but commodity products).

How Salync's Barcode Scanner Works

Salync includes a built-in barcode scanning feature accessible from the /scansection of the platform. Connect a USB or Bluetooth scanner, navigate to the scan screen, and your scanner is ready to use within any of Salync's inventory workflows.

In goods-in mode, scanning a product barcode pulls up the corresponding SKU and allows you to enter the received quantity against an open purchase order. The system updates your stock levels and logs the receipt against the PO automatically. In stocktake mode, scanning each item builds a count that is compared against your system stock levels at the end of the session, with discrepancies highlighted for investigation. In pick/pack mode, scanning confirms each item before dispatch and decrements stock in real time.

Because Salync is a multi-channel platform, a stock update triggered by a scan propagates immediately to all connected channels — your eBay, Amazon, and Shopify listings are updated automatically. This means the moment you confirm a pick with a scan, every channel that lists that product reflects the reduced available quantity. No manual channel updates required.

Common Barcode Mistakes

A barcode system only works if it is used consistently. These are the most common mistakes that undermine accuracy despite having scanning hardware in place:

• Scanning without confirming the system response. A scanner beeps when it reads a barcode — but that does not mean the scan was acted on correctly. The operator should always glance at the screen to confirm the system has matched the scan to the correct product and registered the action.
• Not labelling products that lack barcodes. If some products in your warehouse have no barcode, those products will be handled manually — which reintroduces the error risk that scanning was meant to eliminate. Label everything.
• Using duplicate EAN codes across different variants. A common mistake is using the same EAN for different colours, sizes, or configurations of a product. Each variant needs its own unique barcode.
• Applying barcode labels over the existing manufacturer barcode.This creates confusion when both barcodes are present on the same item. If you are adding internal labels, apply them to a different surface of the packaging from the existing manufacturer barcode.
• Damaged or low-quality label print. A scanner can only read a clear, undamaged barcode. Print at the correct resolution (minimum 203 DPI for barcode labels, ideally 300 DPI), use good-quality label stock, and replace labels that have been damaged in storage.
• Not updating the system when a barcode changes. If a product is relaunched by a manufacturer with a new EAN, your system still points to the old barcode. Scans of the new barcode will fail until the record is updated.