All barcode types require a certain amount of light space (or quiet zone) to the left and right of the code. This enables the scanner to differentiate between the barcode and surrounding graphics. Should the wrong type of graphic image or colour intrude on the light margin, there is a risk that the barcode will not decode, or worse, will decode incorrectly.

One of the most common causes of bad reads is light margin incursion. For this reason, some symbologies employ a method of protecting the quiet zone. For example, an unbroken rule or box may be defined around the code. With the EAN-13 barcode, a human readable character appears to the left of the code but not on the right. In some countries, a recent change to the EAN-13 symbol specifications now recommends that a Light Margin Indicator (>) be placed on the right of the code, in the human readable field, with the tip aligned with the outer edge of the light margin to dissuade designers from placing graphics within the quiet zone.

Minimum Light Margins (EAN-13):

Left Light Margin
Right Light Margin
2.91mm 80% 1.85mm
3.09mm 85% 1.97mm
3.27mm 90% 2.08mm
3.45mm 95% 2.20mm
3.63mm 100% 2.31mm
3.82mm 105% 2.43mm
4.00mm 110% 2.55mm
4.18mm 115% 2.66mm
4.36mm 120% 2.78mm
4.54mm 125% 2.89mm
4.72mm 130% 3.01mm
4.91mm 135% 3.12mm
5.09mm 140% 3.24mm
5.45mm 150% 3.47mm
5.81mm 160% 3.70mm
6.18mm 170% 3.93mm
6.54mm 180% 4.16mm
6.90mm 190% 4.39mm
7.26mm 200% 4.62mm

Also refer A - EAN-13.


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