SKU generator

What a good SKU looks like

TSH-RED-M tells you the product, the color and the size before you look anything up. The most important part goes first, so the codes sort together in a spreadsheet. Each part stays the same length, so the whole list lines up.

The parts of a good SKU

Part	Example	Tip
Product line	TSH	Start with a letter, and keep it to 2 to 4
First option	RED	Agree one short form per value, and write it down
Second option	M	Sizes can stay as they are
Running number, if any	007	Leave room to grow, so 007 rather than 7

Build a list in four steps

1. Type a prefix for this product line.
2. Fill in your option lists, with commas between values. Three colors and four sizes make 12 SKUs, and adding a third list of 2 makes 24.
3. Choose a separator, and turn on a running number if your products have no options to tell them apart.
4. Download the CSV and open it in your spreadsheet or import it to your store. Select any code to see it as a barcode, then download that barcode for a shelf or bin label.

Warnings worth reading

The tool flags these as it builds your list. None of them stops you, since it is your code.

Warnings the SKU generator raises and why

Warning	Why it matters
The same code twice	Two products sharing a code is the mistake a SKU exists to stop. Shortening Black and Blue to 2 letters gives BL twice
Starts with zero	Spreadsheets strip leading zeros, so the code changes without telling you
All digits, 8 to 14 long	It looks like a UPC or EAN, and someone may treat it as one
O next to 0	People misread them when keying by hand
Over 16 characters	Shopify advises staying under this, and long codes print wide and invite typos
Over 50 characters	eBay's published limit

What selling platforms say about SKU length

Few platforms publish a firm number, so a short code is the safe choice. These come from each platform's own documents.

SKU length limits and advice, platform by platform

Platform	What it says
eBay	50 characters at most, or 80 for a variation
Shopify	Keep it short, such as no more than 16 characters, using letters, numbers, dashes and the underscore
Amazon	SKUs are usually 8 to 10 letters and numbers, offered as a typical size and not a rule
Etsy	Advises 4 to 8 characters and no symbols
Walmart Marketplace	Gives the limit only through its seller API

SKU, UPC and ASIN side by side

Who makes and who reads a SKU, a UPC and an ASIN

Code	Who makes it	Who understands it
SKU	You	You and your software
UPC or EAN	Built from a number licensed through GS1	Every retailer and marketplace
ASIN	Amazon	Amazon only

A SKU never replaces a UPC when a retailer wants one. The guide on what a SKU is goes further into choosing a format and rolling it out. The licensed number is in how to get a UPC code.

A worked list

With prefix MUG, options WHT, BLK, and 11OZ, 15OZ, you get MUG-WHT-11OZ, MUG-WHT-15OZ, MUG-BLK-11OZ and MUG-BLK-15OZ. Each is 12 characters and starts with a letter, with no duplicates. At a 0.33 mm narrow bar, a Code 128 barcode for one of them is 61.71 mm wide with clear space.

Keep the barcodes short by keeping the codes short. Every extra character adds 3.63 mm at that size. If you need something much smaller, a Data Matrix code holds the same text in a square under 9 mm wide. The barcode generator draws a single stock code in any of 10 formats. A retail number for the same item is drawn by the UPC generator.

Finding and labeling the codes later

Once the list is in your system, the codes show up in a different place on each platform. Where to find a SKU number maps them out for sellers and buyers. To print a sheet of labels from the CSV, making barcodes in Excel and in Word cover the mail merge route.