Instant Barcode Generator

Retail systems reject a barcode that is one digit wrong, and you find out at the till. This barcode generator encodes your own SKU as Code 128, UPC-A or EAN-13, calculates the check digit for you, shows the correct print size, and downloads a scannable PNG. Free, no account, and no watermark on the file you get back.

Code / SKU

Symbology

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Pick the format before you pick the number

Most barcode problems start here. The three formats this tool produces are not interchangeable, and choosing the wrong one is why a label scans fine on your phone and fails at a supermarket till.

Code 128 is for internal use: your own stock numbers, asset tags, shelf locations. It takes letters as well as digits and any length. UPC-A is the twelve-digit format used at retail in the United States and Canada. EAN-13 is the thirteen-digit equivalent used almost everywhere else. Both are fixed length and digits only.

Check digits, and why the last number is not yours

UPC-A and EAN-13 end in a check digit that is calculated from the digits before it, not chosen. The scanner recalculates it and rejects the code if it does not match. This tool works out that digit for you, which removes the single most common cause of a barcode that will not scan.

Code 128 has its own internal checksum that is never printed, so there is nothing for you to get wrong there.

Which format for which job

Format	Length	Accepts	Use it for	Needs GS1
Code 128	Any	Letters and digits	Internal stock, assets, shelves	No
UPC-A	12 digits	Digits only	Retail in US and Canada	Yes
EAN-13	13 digits	Digits only	Retail outside North America	Yes
EAN-8	8 digits	Digits only	Small packs with no room	Yes

The last column is the one that catches people out. A number you invent will encode and print perfectly, and it will still be rejected by a retailer, because retail numbers have to be issued by GS1 so that no two products in the world share one. This tool encodes and check-digits. It does not issue.

Printing it so it actually scans

More barcodes fail at the printer than in the encoder. Five things to get right:

Size. A full-size EAN-13 is 37.29 mm wide by 25.93 mm tall. Scaling below about 80 percent of that starts costing you reads.
Quiet zone. Leave clear space either side, at least ten times the width of the narrowest bar. Text or a border pressed against the code will break it.
Contrast. Black on white. Red bars are invisible to many scanners, and light grey on white fails outright.
Do not stretch. Scale width and height together. A squashed code changes the bar ratios.
Print at native resolution. A code resized in a word processor picks up blur that a thermal label printer will not.

Test one printed label with a real scanner before you print five hundred.

Printing it so it actually scans

More barcodes fail at the printer than in the encoder. Five things to get right:

Size. A full-size EAN-13 is 37.29 mm wide by 25.93 mm tall. Scaling below about 80 percent of that starts costing you reads.
Quiet zone. Leave clear space either side, at least ten times the width of the narrowest bar. Text pressed against the code will break it.
Contrast. Black on white. Red bars are invisible to many scanners, and light grey on white fails outright.
Do not stretch. Scale width and height together. A squashed code changes the bar ratios.
Print at native resolution. A code resized in a word processor picks up blur a thermal printer will not.

Test one printed label with a real scanner before you print five hundred.

Frequently asked questions

Choose Code 128 for internal codes, asset tags, shelf labels and stock control, because it accepts letters and numbers and there is no registration involved. Choose UPC-A or EAN-13 only for products sold through retailers, and only using a number issued to your company. UPC-A takes exactly 12 digits and EAN-13 takes exactly 13, so a shorter entry will not encode.

The image the instant barcode generator produces is a correctly drawn barcode, and it will scan. What it cannot do is give you the right number for retail. Retail codes are allocated to a registered company prefix so that no two products share an identifier, so obtain your number through the official process first, then encode it here and print it.

Follow the print size note on the card, which suggests roughly 50 to 70mm wide at 300dpi for a standard label. Keep the white space either side of the bars, known as the quiet zone, and never stretch the image in one direction only. If a run has to be smaller, test scan a printed sample before committing to the full batch.

The barcode is drawn in your browser from the characters you type, so the SKU never becomes part of a saved record on the page, and nothing is kept once you close the tab. Downloading gives you the PNG on your own device. For internal stock codes and asset tags that means you can generate labels without routing product data through a third party service.

Tools for stock and labels

Random Letter Generator for prefix letters when you are designing an internal SKU scheme.
Random Password Generator for the random strings some asset tagging systems use.
Random Object Generator for test items when you are trialling a labelling workflow.

A labelling system needs a code scheme before it needs barcodes. Letter and string tools help settle the scheme first, then everything after that is printing.