Ecommerce
What Is a SKU? How to Create SKU Numbers for Your Inventory (With Examples)
A block system you can set up in an afternoon, SKU examples for apparel, beauty and food, when you also need a UPC, and the mistakes that quietly wreck your stock counts.
What is a SKU? It's the internal code you give each product, and each size, color or variant, so you always know how many you have and never ship the wrong one. You make it up yourself, for free, but without a system you end up with codes nobody can read.
In 2026 we asked ChatGPT in the US, Spain and Brazil for a SKU system for T-shirts in 3 sizes and 4 colors. In the US it suggested codes like TS-BLK-S, with no design block, so a second design would collide with the first. In Spain it dropped a color and listed 9 SKUs instead of 12. Here's a system that holds up.
You'll get the meaning, when you also need a UPC, how to create SKU numbers in 6 steps and examples to copy. It's part of our ecommerce section.
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What is a SKU? Meaning and what SKU stands for
A SKU identifies each product variant you stock and sell separately, so you can track inventory without mix-ups.
A SKU, short for stock keeping unit, is an alphanumeric code a business creates to identify each item it stocks and sells separately: one model, in one size and one color. It's internal, so two stores can give the same product completely different SKUs, and nobody has to approve yours.
What does SKU stand for? Stock keeping unit, said as "skew" or letter by letter. And what is a SKU number? The same code, even when it contains letters; people just add the word number. That's the SKU meaning in practice. What it isn't: a universal code. GS1 US, which issues UPCs, puts it plainly in its GTIN guide: a SKU is strictly internal.
How many SKUs does one product have?
As many as the combinations you sell separately: sizes times colors. A tee in 3 sizes and 4 colors is 12 SKUs, and a second design adds 12 more. If a variant doesn't change your stock, like engraving you do on demand, it doesn't need its own code.
SKU vs UPC: when you need each one
You always need a SKU for your own stock; you need a UPC when you sell on marketplaces or to retailers that scan at checkout.
| SKU | UPC (GTIN-12) | |
|---|---|---|
| Who creates it | You | Your company, using a GS1 US prefix |
| Format | Letters, numbers and dashes, your choice | 12 digits |
| Same in every store? | No | Yes |
| What it's for | Inventory, orders and shipping | Letting marketplaces and retailers recognize the product |
| Cost | Free | GS1 US licensing fees |
Do I need a UPC if I only sell on my own site?
No. If you only sell on your own site, SKUs are enough. Once you list on marketplaces or sell to physical stores, you'll usually be asked for one. What you should never do is use a supplier's UPC as your SKU: switch suppliers and the UPC changes, and your sales history for that product breaks.
SKU vs barcode: are they the same?
No. The SKU is the code; a barcode is a way to print a code so a scanner can read it. You can print your SKU as a Code 128 barcode, which handles letters and numbers, for shelves and bins. The barcode on retail packaging usually carries a UPC instead, and one box can carry both labels.
How to create SKU numbers, step by step
Define your blocks, lock their order and abbreviations in a table, then generate the codes with a formula. One afternoon covers your whole catalog.
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List what changes your stock
Model, color, size, capacity or flavor. If two units are sold and counted separately, they need different codes.
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Lock the order of the blocks
From general to specific: type, model, main variant, secondary variant. The same order across the whole catalog.
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Build an abbreviation table
Three letters per value, always the same: TEE for T-shirt, BLK for black, BLU for blue. It's your inventory's dictionary.
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Remove anything confusing
No spaces, slashes or special characters. In blocks with digits, avoid O and I, which look like 0 and 1, and never start a code with zero.
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Generate codes with a formula
With type in A2, model in B2, color in C2 and size in D2, type
=A2&"-"&B2&"-"&C2&"-"&D2and drag down. It works the same in Excel and Google Sheets. -
Label it and never reuse a code
Print each SKU as a Code 128 barcode with our barcode generator and stick it on the shelf. A retired SKU never goes to another product.
If you have lots of variants, this prompt does the heavy lifting and checks the result:
Act as the inventory manager for an online store. Here's my product list with variants: [paste the list]. Propose a three-letter abbreviation table for types, models, colors and sizes, with no special characters and no O or I in blocks that contain digits. Generate SKUs in the format TYPE-MODEL-COLOR-SIZE, check that no two are identical and that the total matches the number of combinations. If anything is missing, write [MISSING].
How many characters should a SKU be?
Eight to 12 is the most common advice for codes that are easy to read and type, and never more than 50. That's the maximum Google Merchant Center accepts for a product ID, according to its help page on the id attribute, checked in 2026. Google also recommends using your SKU as that ID and never changing it once assigned.
SKU examples you can copy
These SKU examples follow the same block system and work as a template for apparel, beauty, food or gifts.
| Business | Product | SKU | How it reads |
|---|---|---|---|
| Apparel | Lake tee, black, medium | TEE-LKE-BLK-M | Type, model, color, size |
| Footwear | Dune sneaker, sand, size 9 | SNK-DUN-SND-9 | Type, model, color, size |
| Beauty | Calm face cream, 2 oz | CRM-CLM-2OZ | Type, line, size |
| Food | Habanero hot sauce, 5 oz | SAU-HAB-5OZ | Type, flavor, size |
| Gifts | Lavender candle 3-pack | PCK-CND-LAV-3PK | Pack, product, scent, units |
| Ceramics | Harbor mug, 12 oz, blue | MUG-HBR-12-BLU | Type, model, capacity, color |
Look at what none of them include: price, supplier or date. Those change, and a SKU has to last as long as the product. That's the real lesson behind every SKU number example above.
Should a SKU include the price?
No. Prices change with sales, increases and channel pricing, and the code has to stay put. Leave the supplier out too: if you switch factories, the product is the same to your customer, and so is its SKU.
Inventory spreadsheet with SKUs: columns and formulas that work
An inventory spreadsheet that doesn't drift needs two tabs: Products, with one row per SKU, and Moves, with one row per stock change. You never type a stock number; the sheet calculates it.
- Products: SKU, name, cost, price, reorder point, in stock and status.
- Moves: date, SKU, type (In or Out), quantity and note.
Name three columns on the Moves tab: MoveSKU, MoveType and MoveQty. In Excel, use the Name Box next to the formula bar; in Google Sheets, go to Data and Named ranges. With the SKU in A2, the stock formula is:
=SUMIFS(MoveQty,MoveSKU,A2,MoveType,"In")-SUMIFS(MoveQty,MoveSKU,A2,MoveType,"Out")
This one, in the status column, flags a SKU when stock (F2) falls below the reorder point (E2): =IF(SIGN(F2-E2)=-1,"Reorder","OK").
A made-up example: the mug MUG-HBR-12-BLU has 40 units in and 28 out, so 12 are left. With a reorder point of 15, the sheet shows "Reorder". Add a drop-down of your SKUs to the SKU column on the Moves tab so a typo can't create a ghost product.
A spreadsheet doesn't sync in real time. Once the same SKU sells on several channels at once, an inventory app starts to pay for itself.
Where the SKU number goes: labels, listings and your store
The SKU label goes on the shelf, the product or its box, and the SKU number must be identical on your site, in your warehouse and on every marketplace.
The SKU is the thread that ties everything together: your product page, the order line, the warehouse label and, if you use a fulfillment partner, their inventory. If one system says TEE-LKE-BLK-M and another says TEELKEBLKM, they count two different products and your stock stops adding up.
Put it next to every entry in your product catalog too, so buyers can order by code. And in your online store, the SKU often becomes the product ID in your Google feed, one more reason to treat it as carefully as your ecommerce SEO.
SKU rationalization: how to cut the SKUs that don't earn their keep
SKU rationalization is a review of your range to cut or merge the SKUs that cost more to keep than they bring in. Every SKU ties up cash, shelf space and listing time, so a long tail of slow ones quietly drags the rest.
- Export 12 months of sales per SKU: units, revenue and margin.
- Rank them by revenue. In most ranges a small share of SKUs earns most of the money. The 80/20 rule is a rule of thumb, not a law, so check it with your own data.
- Flag the candidates: low sales and low margin and no strategic job, such as an entry-level price, a gift option or a seasonal slot.
- Decide what to do: cut it, merge variants (drop the color that sells 2 in 100), bundle it or discount it to clear stock.
- Retire it in your sheet. Mark it retired. Never delete the row and never reuse the code.
An invented example with realistic numbers: a shop with 120 SKUs finds that 18 bring in 62% of revenue and 31 sold fewer than 5 units in a year. If each of those 31 has 8 units on the shelf at a $6 average cost, that's 31 × 8 × $6 = $1,488 of cash sitting still. Before cutting, check whether a slow SKU is the one customers add to the cart next to a best seller.
Frequently asked questions about SKUs
What is another term for SKU?
Depending on the system, you'll see item number, product code, stock number or simply part number. Shopify and most ecommerce platforms label the field SKU, while accounting and ERP tools often say item number. Retailers add their own names too, like a store SKU or an item number on the shelf tag. Whatever the label, it should hold your internal code, not the UPC printed on the package.
How do I find out my SKU?
If it's your product, open your store platform or your product spreadsheet: every product or variant has a SKU field. If you're a shopper, look at the product page, the shelf tag or your receipt. Big retailers such as Home Depot and Walmart show their own item numbers on product pages and let you search their sites with them. Remember that the same product carries a different SKU at each store.
Is a SKU the same as a serial number?
No. A SKU identifies a type of product, such as a black medium Lake tee, and every identical unit shares it. A serial number identifies one physical unit, so no two are the same. Electronics and tools often carry both: the SKU tells the store which model it is, and the serial number handles warranty claims, repairs and theft reports for that exact unit.
What is GTIN?
GTIN stands for Global Trade Item Number, the GS1 identifier that labels a product the same way in every store and marketplace. It comes in four lengths: GTIN-8, GTIN-12, GTIN-13 and GTIN-14. In the US, the familiar UPC barcode carries a GTIN-12, and EAN codes from other countries are GTIN-13. You get them by licensing a company prefix from GS1 US, not by inventing numbers.
What is a SKU on Amazon?
On Amazon, the seller SKU is the code you assign to each of your listings so you can manage stock and orders; you choose it, just like in your own store. It is different from the ASIN, which is Amazon's catalog number for the product page, and from the FNSKU, the label Amazon uses to identify your units in its fulfillment centers. Use the same seller SKU you use on your site and in your spreadsheet.
Should I use a SKU generator?
A SKU generator saves time, but only if it follows your rules. Before using one, decide your blocks, their order and your abbreviations, or it will produce random strings nobody can read. A spreadsheet formula is a perfectly good generator for most small stores, and many ecommerce platforms can build SKUs from product options. Whatever you use, check that every code is unique and never reused.