How to Create SKU Numbers (2026): Format, Examples and Rules

How to create SKU numbers: pick 3 to 5 parts in a fixed order (category or brand, product, then variants such as color and size), give each part a 2–4 character code, and join them with hyphens, like TS-CREW-BLK-M. Keep SKUs under about 20 characters, letters and numbers only, and never reuse one. A SKU is your own code; you don't buy it.

A SKU (stock keeping unit) is the label you use to track one exact sellable item: one product, in one color, in one size. Every marketplace and inventory app asks for one, and a messy system turns into oversells, wrong picks and spreadsheets nobody can read. This guide covers what a SKU is and how it differs from a UPC barcode, a simple format you can copy, examples for common product categories, and the mistakes that cause trouble later.

What is a SKU number?

A SKU is a code you assign to each distinct item you stock so you can count it, find it and sell it without confusion. If a T-shirt comes in 3 colors and 4 sizes, that's 12 SKUs, because a buyer who orders a black medium needs exactly that shirt. A well-made SKU also tells you what the item is at a glance: anyone in your team can read TS-CREW-BLK-M as a black, medium crew-neck tee.

SKUs connect everything in your back office: inventory counts, shelf or bin labels, purchase orders, your store, each marketplace listing and your accounting. When the same SKU appears in all of them, you can sync stock between channels and see which variants actually sell.

What is the difference between a SKU and a UPC?

A SKU is your private code; a UPC is a public product number that every retailer reads the same way. You create SKUs however you like, but UPCs (and EANs, collectively called GTINs) are licensed through GS1, and marketplaces such as Amazon check them against GS1's database. Most sellers need both: a SKU for each variant in their own system and, where the channel requires one, a GTIN.

If you're unsure whether your channel needs a barcode at all, our guide do I need a UPC barcode to sell online? walks through Amazon, Etsy, Shopify, eBay and Walmart.

How do you create a SKU number step by step?

Decide the parts once, write them down, and apply the same pattern to every product. The whole job takes about 20 minutes for a small catalog.

1. List what makes your items different. For apparel that's style, color and size. For candles it might be scent and size. For parts, model and finish.
2. Choose the order, general to specific. Category or brand first, then product, then variants. Related items then sort together in any spreadsheet.
3. Write a short code list for each part. BLK for black, NVY for navy, S/M/L/XL for sizes, 11OZ for an 11 oz mug. Keep it in a shared sheet so everyone uses the same codes.
4. Pick one separator. Hyphens are the safest choice. Avoid spaces, slashes, dots and underscores, which some systems and barcode fonts treat differently.
5. Add a running number only if you need it. Useful when products share the same attributes, such as many prints of the same size: ART-PRT-A4-001, ART-PRT-A4-002.
6. Check for duplicates and length. Two products must never share a SKU, and every SKU should fit the shortest limit of the platforms you sell on.
7. Label the stock. Print the SKU on shelf and bin labels, optionally as a Code 128 barcode so a scanner can read it.

To skip the manual work, our free SKU generator builds SKUs from a brand code, product name, up to three attributes and an optional running number. It can expand every color and size combination at once (3 colors × 4 sizes gives 12 SKUs), flags duplicates and codes over your length limit, strips accents and symbols, and downloads a CSV. It runs in your browser, so your product list isn't uploaded.

What does a good SKU format look like?

A good SKU is short, readable and built the same way every time. This template works for most small catalogs:

SKU examples by product category

These examples use the same general-to-specific order. Copy the pattern that's closest to your products and swap in your own codes.

For resale and vintage, a date-plus-number SKU works better than descriptive codes because every item is different. Some resellers add a storage location instead, such as B03-0142 for bin 3, item 142, so they can find it fast when it sells.

How long should a SKU be?

Aim for 8 to 20 characters. That's long enough to carry meaning and short enough to read on a pick list or a small label. Platform limits are higher, but they differ, so design for the strictest one you use.

Limits can change and vary by tool, so check the field in your seller account if you plan to use long codes.

SKU do's and don'ts

Most SKU problems come from breaking one of a few simple rules.

Also keep prices, dates and supplier names out of SKUs. Those details change, and a SKU should not. Watch for abbreviation clashes too: Blue and Blush both shorten to BLU, so pick distinct codes such as BLU and BLS.

Can you turn a SKU into a barcode?

Yes. A Code 128 barcode can encode letters, numbers and hyphens, so you can print your SKU as a scannable label for shelves, bins and internal stock counts. Our free barcode generator makes Code 128 labels (plus UPC-A, EAN-13, EAN-8 and ITF-14) as PNG or SVG, up to 50 at once. These barcodes are for your own use: the tool draws a barcode for a number you already have, and it does not issue GS1-registered product IDs, so it can't replace a UPC for Amazon or retail.

Keeping SKUs organized as you grow

• One master sheet. SKU, product name, variant values, GTIN (if any), cost and supplier in one place. Every channel pulls from it.
• Same SKU on every channel. Use the identical SKU on Shopify, Etsy, Amazon and eBay so inventory apps can match them.
• Name photo files by SKU. TS-CREW-BLK-M_front.jpg keeps images matched to variants and makes relisting easy.
• Review once a quarter. Archive discontinued SKUs instead of deleting them, so old orders still make sense.

With SKUs in place, a product catalog and consistent product titles are much easier to build. If you list on several marketplaces, check each one's listing character limits before you bulk upload.

Frequently asked questions

How do I create a SKU number for my products?

Choose a fixed order of parts, such as category, product, color and size, give each part a short code, and join them with hyphens: TS-CREW-BLK-M. Use letters and numbers only, start with a letter, and give every variant its own SKU.

Do I need to buy SKU numbers?

No. SKUs are free and you create them yourself. What you may need to buy is a UPC or EAN barcode number, which is licensed through GS1 and used by marketplaces to identify products.

Is a SKU the same as a barcode?

No. A SKU is your internal stock code, while a barcode is a way of printing a number so a scanner can read it. You can print a SKU as a Code 128 barcode for internal use, but that is not a UPC.

How many characters should a SKU have?

Around 8 to 20 characters is easiest to read and fits every major platform. Amazon sellers commonly cite a 40-character cap and eBay's API allows 50, so check the field in your seller account if you use longer codes.

Can two products have the same SKU?

They shouldn't. Each SKU must point to exactly one item, including each color and size. Shared SKUs cause wrong stock counts and wrong shipments.

Should SKUs include numbers or letters?

Both work. Letters make SKUs readable (BLK for black) and numbers work for sizes or running counts. Avoid starting with zero, because spreadsheets often drop leading zeros.