Barcode size: minimum, quiet zones and choosing the label
A barcode that is too small, too short or too close to the label edge is the most common cause of scanning problems. This guide gives the dimensions to respect and the minimum label width for your printer.
The module: the barcode’s unit of measure
All barcode dimensions follow from the width of its narrowest bar, called the module (or X-dimension). Wide bars and spaces are 2, 3 or 4 modules.
For an EAN-13, nominal size (100 %) means a module of 0.33 mm. The standard allows 80 % to 200 %, a module of 0.264 mm to 0.66 mm. For retail, stay at 100 % or above where you can.
| EAN-13 size | Module | Total width incl. quiet zones | Bar height |
|---|---|---|---|
| 80 % (minimum) | 0.264 mm | 29.8 mm | 18.3 mm |
| 100 % (nominal) | 0.330 mm | 37.3 mm | 22.9 mm |
| 150 % | 0.495 mm | 55.9 mm | 34.3 mm |
| 200 % (maximum) | 0.660 mm | 74.6 mm | 45.7 mm |
Quiet zones: the blank margin you need
On each side of the barcode, a blank area lets the scanner find where the symbol starts and ends. For an EAN-13 it is 11 modules on the left and 7 on the right, 3.6 mm and 2.3 mm at 100 %. For Code 128 and Code 39, allow at least 10 modules each side.
Text, a border, a logo or the edge of the label inside this zone can make the barcode unreadable. The generator reserves these margins automatically.
Don’t cut the bars short
Reducing bar height (truncation) to save space is tempting on small labels. A handheld scanner, which reads one line, usually copes. A fixed checkout scanner, which reads from several angles, needs the full height. For retail products, keep close to the height in the table.
What label width does an EAN-13 need?
Allowing 1.5 mm of margin on each side of the label, this is the largest EAN-13 that fits:
| Label width | Largest EAN-13 | Advice |
|---|---|---|
| 38 mm (65 per sheet) | 94 % | Possible, but bar height is heavily reduced on 21 mm. |
| 40 mm | 99 % | Just enough. |
| 50 mm | 126 % | A good choice for products. |
| 52.5 mm (32 and 40 per sheet) | 133 % | Comfortable. |
| 63.5 mm and wider | 160 % and more | Plenty of margin. |
Thermal printers: think in dots
A thermal printer only prints whole dots. At 203 dpi a dot is 0.125 mm; at 300 dpi, 0.085 mm. The module should be a whole number of dots, otherwise bars are rounded unevenly.
| Resolution | Dots per module | Module | EAN-13 size | Minimum width incl. quiet zones |
|---|---|---|---|---|
| 203 dpi | 2 | 0.250 mm | 76 % (too small) | 28.3 mm |
| 203 dpi | 3 | 0.375 mm | 114 % | 42.4 mm |
| 203 dpi | 4 | 0.500 mm | 152 % | 56.6 mm |
| 300 dpi | 3 | 0.254 mm | 77 % (too small) | 28.7 mm |
| 300 dpi | 4 | 0.339 mm | 103 % | 38.3 mm |
| 300 dpi | 5 | 0.423 mm | 128 % | 47.8 mm |
In practice, on a 203 dpi printer (most desktop models) an EAN-13 needs a label at least 45 to 50 mm wide. A 300 dpi printer can go down to 40 mm. Choose your printer’s resolution in the generator: it does the rounding and shows the size you get.
And Code 128?
Code 128 has no fixed nominal size for internal use; its width depends on the number of characters. With a typical laser scanner, aim for a module of at least 0.25 mm (2 dots at 203 dpi) and a bar height of at least 10 mm. Below that, test with your own scanner before printing a whole run.