What is a barcode?
A barcode represents data as black and white bars of varying widths that scanners read in a fraction of a second. Barcodes price products at checkout, track inventory in warehouses, and identify items in libraries, hospitals, parcel shipping and event ticketing.
Available barcode types
| Type | Data | Use |
|---|---|---|
| Code 128 | Letters, digits, symbols | Inventory, shipping, internal assets, tickets |
| EAN-13 | 13 digits | Retail products worldwide |
| UPC-A | 12 digits | Retail products in the US and Canada |
| EAN-8 | 8 digits | Small products with limited space |
The check digit
The last digit of EAN and UPC codes is a check digit computed from the others to catch scanning errors. You don't need to calculate it: enter 12 digits for EAN-13 and the tool adds it; enter 13 and it verifies it and warns you if it's wrong.
Do I need to register barcode numbers?
To sell through major retailers or marketplaces like Amazon, you need official EAN/UPC numbers from GS1 in your country — they're globally unique and tied to your company. For internal use such as inventory tracking or pricing in your own shop, a Code 128 barcode with your own numbering is enough.
Printing tips
- Print black on white for best results; light or red bars confuse many scanners.
- Don't shrink the barcode too much, and leave white quiet zones on both sides.
- Use SVG for professional printing — it stays crisp at any size.
- Test before a big print run with the Barcode Scanner on your phone.
Frequently Asked Questions
Can I use these barcodes in major stores?
You need official GS1-registered EAN numbers. The tool draws a barcode for any number but doesn't issue registered numbers.
What's the difference between QR and barcodes?
Linear barcodes hold little data in one dimension; QR codes store much more in two dimensions and are easy to scan with phones.
Can I encode lowercase letters?
Yes, Code 128 supports upper and lower case letters, digits and symbols.
Why do I see “Invalid check digit”?
The last digit doesn't match the official calculation. Remove it and enter 12 digits so the tool computes it.
Which download format is best?
SVG for professional print, PNG for documents and websites.
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