Barcode print size and quiet zone: the numbers that make barcodes scan
Most barcodes that fail at a checkout or a warehouse dock fail because of size: too small, cut too short, or crowded by other artwork. The rules are simple once you know the three numbers that matter.
The three numbers
- X-dimension (module width): the width of the narrowest bar. Every other bar and space is a whole multiple of it, so it sets the size of the whole barcode.
- Bar height: how tall the bars are. Taller bars can be scanned at a steeper angle and survive scratches.
- Quiet zone: the blank space before the first bar and after the last. The scanner uses it to find where the barcode starts and ends.
Sizes for common barcodes
| Barcode | X-dimension | Bar height | Quiet zone |
|---|---|---|---|
| EAN-13, UPC-A, ISBN | 0.330 mm at 100% (0.264 to 0.660 mm) | 22.85 mm at 100% | EAN-13: 11X left, 7X right. UPC-A: 9X each side |
| EAN-8 | 0.330 mm at 100% (0.264 to 0.660 mm) | 18.23 mm at 100% | 7X each side |
| UPC-E | 0.330 mm at 100% (0.264 to 0.660 mm) | 22.85 mm at 100% | 9X left, 7X right |
| ITF-14 on cartons | 0.495 to 1.016 mm | At least 31.75 mm | At least 10X, plus bearer bars |
| GS1-128 on logistics labels | 0.495 to 1.016 mm | At least 31.75 mm | At least 10X |
| Code 128, Code 39, Codabar | 0.25 mm or more for label printers | 15% of the length or 6.35 mm, whichever is more | At least 10X |
| Data Matrix | 0.25 mm or more for handheld imagers | Square, set by the module count | At least 1X all round |
| PDF417 | 0.25 mm or more | Rows at least 3X tall | At least 2X all round |
Retail barcodes: magnification
EAN and UPC barcodes have a fixed design size, called 100%, with a 0.330 mm module. You may scale the whole barcode between 80% and 200%. Below 80% the bars get too thin for checkout scanners to read reliably. If an EAN-13 at 80% (about 29.8 mm wide with its margins) still won't fit, ask your GS1 office about an EAN-8 number.
Don't shrink the height on its own. Cutting the bars short, called truncation, is allowed by GS1 only as a last resort, and a truncated code is hard to read unless it's held straight in front of the scanner. Checkout scanners read from many angles, and they need the height to do it.
Quiet zones in practice
The quiet zone belongs to the barcode. Keep it free of text, borders, the edge of a label, folds, seams and the edge of a die cut. On an EAN-13 at 100% that's 3.63 mm on the left and 2.31 mm on the right. Some designers print a small > after the digits on the right to remind everyone that the space must stay clear.
Match your printer's dots
A printer can only make bars a whole number of dots wide. If you ask for a 0.33 mm bar on a 203 dpi thermal printer (0.125 mm per dot), it has to round some bars to 2 dots and others to 3, and the uneven bars may not scan. Choose a module width that is a whole number of dots instead:
| Printer resolution | Dot size | Good module widths |
|---|---|---|
| 203 dpi (most thermal label printers) | 0.125 mm | 2 dots = 0.250 mm, 3 dots = 0.375 mm, 4 dots = 0.500 mm |
| 300 dpi | 0.085 mm | 3 dots = 0.254 mm, 4 dots = 0.339 mm, 6 dots = 0.508 mm |
| 600 dpi | 0.042 mm | 6 dots = 0.254 mm, 8 dots = 0.339 mm, 12 dots = 0.508 mm |
Our generator shows the pixels per bar for the resolution you choose. For packaging printed by a print shop, send a vector file (SVG, PDF or EPS) and let the printer apply bar width reduction, which thins the bars slightly to make up for ink spreading on press.
Step by step
- Find the standard for your barcode. Retail codes have a fixed 100% size; logistics and industrial codes have a minimum X-dimension. The table above covers the common ones.
- Pick an X-dimension your printer can hit exactly. Divide by the printer's dot size and round to a whole number of dots.
- Keep the full height and the quiet zones. Leave clear space on both sides and don't cut the bars short to save room.
- Export at the final size. Use SVG, PDF or EPS for print, or a PNG at the printer's resolution placed at 100%.
- Print a proof and scan it. Use the scanner, material and lighting it will meet in real life.
More on what goes wrong: why a barcode won't scan. For QR codes, see the QR code size guide.