Does every product variant need its own SKU?

Yes, if you want accurate inventory. Each size, color or material that you stock separately should have its own SKU, so stock, orders and sales reports track the exact variant.

Can I make up my own SKUs?

Yes. SKUs are internal codes, so you can design any format that suits your catalog. Keep them short, consistent and unique, and avoid reusing old codes for new products.

SKU (stock keeping unit)

A SKU (stock keeping unit) is a unique code a store gives each sellable product variant, so it can track stock, sales and reorders accurately.

What is a SKU?

A SKU, short for stock keeping unit, is an internal code that identifies one specific item you sell. Each variant usually gets its own SKU, so a T-shirt in black size medium has a different SKU from the same shirt in white size large. SKUs are created by the store, not by a global standard, so you can design them to suit your business. For an online store, SKUs matter because they keep inventory counts, order fulfillment, supplier reorders and sales reports accurate. Without clear SKUs, warehouses pick the wrong items and reports mix up variants.

How SKUs work

You give every variant a short code that describes it, often built from parts like product type, model, color and size. For example, a hoodie in navy size large might get the SKU HD-NAV-L, while the same hoodie in grey size small becomes HD-GRY-S. When an order comes in, the warehouse picks by SKU, and your store deducts stock from that exact variant. Sales reports by SKU then show which colors and sizes sell best, so you can reorder the right mix instead of guessing. Clear codes also make returns, stock counts and supplier reorders faster, because everyone refers to the same item the same way.

When to use them

Use SKUs as soon as you hold stock or sell more than a few variants. They are essential when you work with a warehouse or fulfillment partner, sell on several channels, or reorder from suppliers. The benefits are fewer picking mistakes, accurate stock levels and clear sales data per variant. The downsides are small, mostly the effort of setting up a consistent scheme and keeping it clean as your catalog grows. A messy or inconsistent SKU system can cause as many problems as having none, so decide on the format early.

Best practices

Keep SKUs short, readable and consistent, using the same order of parts every time, such as product, color, then size. Use only letters, numbers and dashes, and avoid characters that look alike, like the letter O and the number zero. Do not start SKUs with zero, because spreadsheets often strip it. Never reuse a SKU for a different product, even after one is discontinued. Give every variant its own SKU and record them in your store, your warehouse system and your supplier orders so all systems match. A short written guide keeps everyone on the same format.

SKU vs UPC

A SKU is an internal code that a store creates for its own tracking, and the same product can have different SKUs at different retailers. A UPC, or universal product code, is a standard barcode number registered through an official body and used across retailers and marketplaces worldwide. One product variant has one UPC everywhere it is sold. Stores often use both, with the SKU for internal inventory and the UPC for scanning at retail or listing on marketplaces that require it. Your SKU is the code your team uses every day, while the UPC is the code the outside world scans and checks.

Questions

Does every product variant need its own SKU?: Yes, if you want accurate inventory. Each size, color or material that you stock separately should have its own SKU, so stock, orders and sales reports track the exact variant.
Can I make up my own SKUs?: Yes. SKUs are internal codes, so you can design any format that suits your catalog. Keep them short, consistent and unique, and avoid reusing old codes for new products.