Wide-to-Narrow Ratio
The wide-to-narrow ratio (print ratio) is the width relationship between the wide and narrow elements in a two-width symbology such as Code 39, Codabar, or Interleaved 2 of 5.
What You Need to Know
Two-width symbologies encode data with just two element widths: narrow (typically 1 module) and wide (a fixed multiple). Common ratios range from 2:1 to 3:1. The ratio is a decoding dimension — the scanner identifies characters by comparing element widths against this ratio, so a printed ratio that drifts from the declared one corrupts every character, not just one.
A 2:1 ratio produces the narrowest possible symbol but tolerates the least print distortion; 3:1 is more forgiving on dot-matrix, inkjet, and thermal printers at the cost of roughly 50% more width. Because 2.5:1 has historically been the default in many industries, verify the expected ratio against your trading partners' requirements before mass printing — scanners configured for one ratio will misread symbols printed with another.
Where Wide-to-Narrow Ratio Applies
The classic self-checking alphanumeric barcode: 43 characters, simple structure, still everywhere in industry.
Generate Code 39 →A self-checking numeric barcode with start/stop letters, historically used by libraries and blood banks.
Generate Codabar →A dense digits-only linear barcode that interleaves bar and space character pairs — logistics workhorse for numeric data.
Generate ITF (Interleaved 2 of 5) →The GTIN-14 carton-level barcode: ITF with thick bearer bars, printed directly on corrugated shipping cases.
Generate ITF-14 →