How to Create SKU Numbers That Stay Readable as a Shop Grows

The simplest way to create SKU numbers is to string together short, fixed codes for the attributes that make one item different from another: category first, then style, then colour, then size. TS-CREW-BLK-M is instantly a black crew-neck T-shirt in medium. Settle that pattern before the catalogue grows and every later product slots into it without debate.

What is a SKU?

SKU stands for stock keeping unit. It is a code a business creates for its own use to identify each product variant it stocks and sells. If a customer can choose it separately and it needs its own stock count, it needs its own SKU. Three sizes of the same jumper are three SKUs; a gift bundle containing two items is a fourth.

Unlike a UPC code, which is shared by every shop selling the same product, a SKU means something only inside one business. Two shops can sell the identical item under completely different SKUs, and that is perfectly normal.

Why the format matters

• Picking and packing — staff or a warehouse partner match orders to shelves by SKU.
• Reordering — sales reports by SKU show which sizes or colours run out first.
• Accounting — stock is a current asset, and a clean SKU list makes the inventory figure on a balance sheet far easier to check.
• Multiple channels — the same SKU ties together listings on the shop, marketplaces and wholesale order forms.

Building a format, step by step

1. List every product and variant in a spreadsheet, one row per sellable item.
2. Decide which attributes change the stock. Colour and size usually do; a marketing name usually does not.
3. Write an abbreviation dictionary. Fix two- to four-character codes for each category, style, colour and size, and keep it in the same file.
4. Choose the order of segments from broadest to most specific, and never change it later.
5. Assign codes row by row, then sort the list to spot duplicates.
6. Load them into the shop platform and any stock system, and label shelves or bins to match.

Examples to adapt

Handmade lines work the same way. A maker selling personalised acrylic keychains might give each standard design and shape a SKU and add one extra code for custom orders.

Rules that prevent mistakes

• Start with a letter, not a zero. Spreadsheets often strip leading zeros and quietly change the code.
• Avoid look-alike characters. The letter O and zero, or I, L and one, are easy to misread on a label.
• Use only letters, numbers and hyphens. Spaces, slashes and symbols break some imports and barcode fonts.
• Keep it short. Long codes get truncated on labels and mistyped by hand; most shops stay comfortably under about a dozen characters.
• Leave out things that change. Prices, supplier names and seasons go out of date while the product stays the same.
• Never reuse a retired SKU for a new item, or old sales history will be mixed into the new product's reports.
• Do not copy the manufacturer's part number. It follows someone else's logic and may clash when you add a second supplier.

Common questions

Should SKUs be sequential numbers?

Plain numbers such as 10001, 10002 are unique but tell a packer nothing. A readable format pays off as soon as more than one person handles stock.

What happens to a SKU when an item is on backorder?

Nothing changes. The SKU stays active while its stock count sits at zero or below; once new stock arrives and is received against that SKU, the waiting orders can be filled.

Do photos and files need SKUs too?

It helps. Naming image files with the SKU, as described in our guide to taking product photos with a phone, makes it easy to match every picture to the right variant.

Does the SKU need to appear on the product itself?

Not on the item, but it should be on the shelf or bin label and, where possible, on the outer carton or bag. Many shops print a small sticker with the SKU and a short description so that anyone receiving a delivery or packing an order can match the item without opening the packaging. If the product also carries a printed barcode, keep a record of which barcode belongs to which SKU.

Can I change my SKU format later?

Yes, but it means updating listings, labels, reports and any warehouse records at once. Spending an hour on the format at the start is far cheaper than a migration later.