SKU numbers and barcode labels: how to name your stock

Somewhere in your shop is an item that three people call three different things. The supplier calls it 'WG-16.' The shelf label says 'wood glue, big.' The invoice says 'Adhesive PVA 473ml.' Everyone knows it is the same thing until a new hire orders it three times.

A SKU fixes that. It is a single short code that belongs to one item, in your shop, forever.

What a SKU is, and what it is not

SKU stands for stock keeping unit. It is an identifier you choose for each distinct thing you stock. A barcode, by contrast, is a pattern of bars that a scanner reads. The two are related and not the same.

• The SKU is yours. You invent it and control it.
• The barcode is often someone else's. A manufacturer prints a UPC or EAN on the package, and it is the same in every shop that sells the item.
• You can print your own barcode label that simply encodes your SKU.

Building a code people can read

The best codes are boring. They are short, they sort sensibly, and a person can guess what they mean. A simple pattern is category, then type, then variant.

Rules of thumb

• Keep it short, ideally under twelve characters.
• Use capitals and hyphens, and skip spaces and punctuation that confuse software.
• Never reuse a SKU, even after you stop selling an item.
• Do not embed things that change, such as a supplier's name or a price.
• Write the rules down on one page, so the next person follows them.

Label mistakes that break scanning

A SKU is only useful if it ends up on the shelf. Most scanning trouble is a printing problem, not a software problem.

• Labels printed too small or at low quality, so the bars blur.
• Labels on curved or shiny surfaces, which flex the bars.
• A label stuck over the manufacturer's barcode, so the shelf has two codes and a scanner chooses at random.
• Fading thermal paper in a warm stockroom.
• Barcodes that do not match the item list because the number was typed by hand.

When the supplier's code differs from yours

Your supplier has a code for the item, and so do you. Do not try to merge them. Keep your own SKU as the identity, and store the supplier's code alongside it as a reference. Then a purchase order can carry the supplier's code, where they expect it, while your shelf and your counts use yours.

If you change suppliers, your SKU stays the same and only the reference changes. The shelf label does not need reprinting, your history is unbroken, and a new hire does not have to learn a second naming system.

This is a small decision with a big payoff. Shops that skip it end up with an item list that is half their codes and half someone else's, and a very confused import file.