Barcode Generator

It encodes the full ASCII set, is compact, and is the standard for shipping and internal logistics. It also has an automatic mode that switches to a double-density numeric subset, so long digit strings take roughly half the width of other symbologies.

Usually the quiet zone or the contrast. Leave at least ten times the narrow-bar width of blank space at each end, keep the bars pure black on pure white, and never scale the image non-uniformly. Stretching horizontally is fine; stretching vertically alone distorts the bar widths.