What is a SKU? A practical guide for e-commerce sellers

SKU stands for Stock Keeping Unit. It's the product code you assign to each item in your inventory—an internal shorthand that makes products easy to find, track, and reference across your business.

If you're selling products online, getting your SKU structure right from the start saves countless headaches down the road. A good SKU system speeds up warehouse operations, prevents picking errors, and keeps your inventory accurate across every sales channel.

Why SKUs matter

Think of SKUs as abbreviations for your products. Instead of searching for "Blue ceramic coffee mug, 350ml, matte finish," your team looks for MUG-BLU-350. That's faster to scan on a pick list, easier to communicate, and harder to confuse with similar products.

Every product variant needs its own unique SKU. If you sell a hoodie in three sizes and four colors, that's twelve SKUs—not one. This granularity is what allows you to track exactly which variants sell fastest and which ones sit in your warehouse gathering dust.

When you sell across multiple channels—Amazon, bol.com, your own webshop—each platform uses different identifiers. Your SKU becomes the common thread that connects everything. It's how your inventory system knows that a sale on any channel should decrease the same stock count.

How to structure your SKUs

The best SKUs are short, readable, and follow a consistent pattern. A typical structure moves from general to specific:

[Product Type]-[Attribute]-[Variant]

Use the beginning of the SKU to group similar products together, and the end to distinguish between variants. This way, when you sort your inventory alphabetically, related products cluster together.

SKU examples

Simple product in multiple colors

You sell phone cases in black, white, and blue. Your SKUs could be: CASE-BLK, CASE-WHT, and CASE-BLU. The CASE prefix groups them together, while the color suffix makes each unique.

Apparel with size and color

For a hoodie available in multiple sizes and colors, you add both attributes. A black hoodie in small becomes HOO-BLK-S, medium becomes HOO-BLK-M, and large becomes HOO-BLK-L. Switch to grey and you get HOO-GRY-S, HOO-GRY-M, and so on.

Seasonal collections

If you run seasonal inventory, prefix with the collection. A summer 2024 linen shirt in white, size medium becomes S24-LSH-WHT-M. This lets you quickly filter and manage stock by season when it's time to clear old inventory.

Best practices

Keep abbreviations intuitive. BLK for black, WHT for white, S/M/L for sizes. A new team member should be able to guess what a SKU represents without a reference sheet.

Stay consistent. If black is BLK for shirts, don't make it BK for pants. Pick your abbreviations once and stick with them across your entire catalog.

Put variants last. Structure SKUs so the unique part comes at the end. This groups all variants of a product together when sorted alphabetically.

Avoid special characters. Stick to letters, numbers, and hyphens. Slashes and spaces cause problems when exporting data between systems.

Don't start with zero. Some systems strip leading zeros, turning 0234-BLK into 234-BLK. Start with letters or non-zero numbers.

Managing SKUs in Stockpilot

Stockpilot gives you flexibility in how you connect products to your sales channels. You can match listings by SKU, by barcode, or without matching reference (manually)—whatever fits your workflow. Some sellers have clean SKU systems and match on those. Others rely on barcodes because their suppliers provide them. Stockpilot doesn't force one approach.

When connecting a sales channel like Amazon, bol.com, or your webshop, you choose how to link each listing to your inventory. This means you can start selling across channels even if your SKU structure isn't perfect yet.

During picking and packing, both SKU and barcode display so warehouse staff can verify they're grabbing the right item. Scan the barcode or check the SKU—either works.