Barcodes for Inventory

Stock control starts working when counting means scanning. The symbology to pick, how to design SKU numbers, and the label and scanner choices that make it stick.

The short answer

For internal inventory, use Code 128: it is compact, encodes letters and digits, and carries a built-in check character so a misread comes up as an error instead of the wrong product. Print on thermal-transfer labels, scan with any USB barcode scanner, and keep the barcode as a short SKU — the details belong in your system, not in the label.

You do not need GS1 for internal labels

GS1 membership buys globally unique numbers for products that cross company boundaries — retail checkout, marketplaces, distributors. Inside your own four walls you can number things however you like, free. The moment a barcode has to be scanned by someone else's system, that changes: see GS1 barcode basics before printing UPCs you invented.

Design the SKU before the label

• Short. Every character widens the barcode. 6–10 characters covers most small businesses.
• Structured, lightly. A prefix for category (TS- for t-shirts) helps humans; deep meaning encoded in digits ("position 4 is the warehouse") calcifies fast.
• Unambiguous. If staff will ever read or type one aloud, avoid mixing O with 0 and I with 1.
• One SKU per thing you count. A red shirt in M and L is two SKUs, not one with a note.

Labels and printers

Direct thermal labels need no ribbon but darken with heat and fade in sunlight — right for shipping labels that live for a week. Thermal transfer uses a ribbon and survives years on a shelf edge or a tote. An office laser printer on label sheets is a perfectly good starting point; the barcode label maker lays codes out at true millimetre sizes on Letter or A4 stock, and the bulk generator turns a CSV of SKUs into a ZIP of images in one pass.

Scanners

A basic wired USB scanner behaves as a keyboard: scan, and the SKU "types itself" into whatever has focus — which means even a spreadsheet becomes a working check-in log. Phone cameras (or our in-browser barcode scanner) are fine for occasional counts; dedicated hardware wins the moment volume matters, because it scans first time from any angle a hundred times an hour.

Make the scan the habit

Label the shelf as well as the item, put a scanner at every point where stock moves, and make the rule simple: if it moved, it was scanned. Accuracy comes from the habit, not the hardware.

Sources

Code 128 is specified in ISO/IEC 15417, including the modulo-103 check character. Thermal print durability guidance comes from label-stock manufacturers' published specifications; test on your own material.