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- How to print barcode labels that scan
How to print barcode labels that scan
A barcode that looks fine can still fail at the till. Almost every failure comes down to a few things you can check before you print: width, blank space, contrast, and size.
Keep the narrowest bar wide enough
Scanners measure the narrowest bar and work everything else out from it. GS1 UK gives the nominal narrowest bar of an EAN-13 as 0.33 mm, and a printed code may be down to 80% of that, about 0.264 mm.
This tool works out the narrowest bar on your label. It warns you below 0.25 mm, and below 0.15 mm it will not draw the code. A longer code or a smaller label makes thinner bars. The fix is a larger label, a shorter code, or a QR code.
Leave the blank space
Every barcode needs blank space at both ends, called the quiet zone. It is 10 modules for Code 128 and Code 39, 11 on the left and 7 on the right for EAN-13, 9 on each side for UPC-A, and 4 on every side for a QR code. A module is the width of the narrowest bar. The tool adds the space, so do not let a border, a fold, or the edge of the label cut into it.
Print dark bars on a light background
Black on white is the safest. Weak contrast, coloured bars, and shiny labels that throw back glare all make a code harder to read. Red bars on a white label are hard for scanners that use red light.
Print at 100%
In the print window, choose Actual size or 100%, never Fit to page. Fit to page shrinks the page a little, which changes the width of every bar and moves the labels off their stickers.
Choose the right file
The PDF and the SVG files are made of shapes, so they stay sharp at any size. For a PNG, choose 300 dpi for most label printers, or 600 dpi for very small labels. Do not stretch a PNG in another program, because that blurs the edges and changes the bar widths.
Test before you print a few hundred
- Print one sheet on plain paper at 100%.
- Scan a few labels with the scanner or phone that will be used.
- Print the test sheet and hold it against a real label sheet to check the alignment.
- Move the labels with the right and down boxes until the boxes sit on the labels.
- Print the real sheets with the same settings.
Choose labels that suit your printer
Laser and inkjet printers use different label sheets, so buy ones made for yours. Small thermal printers use rolls. For those, choose Label printer roll, set the size of one label, and say how many labels sit side by side.
Questions
Why will my barcode not scan from a screen?
Screens add glare, and a small code on a screen may be only a few pixels wide for each bar. Zoom in so each bar is several pixels wide, and turn the brightness up.
Can I make the label smaller?
Yes, as long as the narrowest bar stays above the limits. A shorter code lets you use a smaller label.
What does a bar warning mean?
The narrowest bar on your label is thinner than 0.25 mm, and some scanners may struggle. Use a larger label, a shorter code, or a QR code.
Sources
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