Bar Width Adjustment (also referred to as Bar Width Reduction, or BWR) is used to compensate for printing processes that output bars wider or narrower than desired. Commonly, commercial printing equipment will introduce a certain amount of ink spread (a.k.a. press gain) that you should compensate for, since a barcode is made of precise measurements.

The adjustment is specified in dots – that is, the number of dots on a page when printing at a specified resolution. For example, a 600 dpi printer prints 600 dots for every inch. So, an adjustment of "-1 dots" for 600 dpi resolution will result in a bar with reduction of 1/600th of an inch.

If you know the number of dots you wish to use to compensate, simply enter it into the Advanced window of your symbology. Remember that your selection is dependent on the resolution being set properly – when setting Bar Width Adjustment, the resolution matters even if you are saving your barcode as a vector EPS file.

How do I convert from milliinches ("mil")?

If you know the amount of adjustment you need in mils (1/1000 inch), you can convert it to dots using a simple calculation:

(Output Device Resolution) × (Inches of Adjustment) = (Dots of Adjustment)

For example, a 2540 dpi printing process might require 2 mils (0.002 inches) of bar width reduction, so:

2540 dots/inch × 0.002 inches = 5.08 dots

A dot is the smallest unit the printer can output and therefore is the smallest possible unit of adjustment. 5.08 dots is rounded to 5 dots, and an adjustment of "-5 dots" is used.

How do I convert from microns?

Convert from microns to inches using this formula:

(Microns of Adjustment) ÷ (25400 Microns/Inch) = (Inches of Adjustment)

For example, an adjustment of 50 microns would be computed as:

50 microns ÷ 25400 microns/inch = 0.0019685039 inches

Next, use the inches of adjustment in this formula:

(Output Device Resolution) × (Inches of Adjustment) = (Dots of Adjustment)

For example, a 600 dpi printing process might require 50 microns (0.0019685039 inches) of bar width reduction, so:

600 dots/inch × 0.0019685039 inches = 1.18110234 dots

A dot is the smallest unit the printer can output and therefore is the smallest possible unit of adjustment. 1.18 dots is rounded to 1 dot, and an adjustment of "-1 dot" is used.

"Can't you just tell me what to enter?"

No – the answer is different for different types of output devices. Your commercial printer or prepress manager can provide more information on ink spread, and will likely know the term "Bar Width Reduction" and the specification you need while creating your barcode.

Users set this option to achieve technical precision when using certain kinds of printing equipment – if you're using this option, spend the time to fully understand the printing process and find the correct value.

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