Code 93 Barcode Generator

What a Code 93 barcode is

Code 93 is a one-dimensional, continuous barcode symbology developed by Intermec in 1982. Intermec designed it as a successor to Code 39 that achieves higher density by using a nine-module character structure with three bars and three spaces, compared to Code 39's five bars and four spaces across a wider module count.

Code 93 has no dedicated ISO/IEC standard. It is referenced informally in AIM specifications and supported by most barcode readers as a legacy format, but it was never formally standardised under ISO/IEC like Code 128 (ISO/IEC 15417) or Code 39 (ISO/IEC 16388). This is not an editorial oversight — it is a factual difference between Code 93 and its more widely adopted relatives, and it is relevant when specifying a barcode system: equipment vendors are not obliged to certify Code 93 compliance against a published standard.

The native character set is 43 characters: the 26 uppercase letters A–Z, the 10 digits 0–9, and seven special characters: space, hyphen, period, dollar sign, slash, plus sign and percent sign. Full 128-character ASCII is available via four shift characters — denoted ($), (/), (%), (+) — which combine with a following character to represent the 85 additional ASCII values not in the native set.

Code 93 technical specification

Character set, structure and check digits

The dual modulo-47 check character in detail

Code 93's two check characters make it one of the more robust linear symbologies for error detection. The C check is computed by taking the values of all data characters (using the Code 93 character value table where A=10, B=11, ..., Z=35, 0=0, ..., 9=9, and special characters each assigned unique values), then cycling weights 1 through 20 from right to left across the data string, summing the products, and taking the remainder modulo 47. The remainder maps to the corresponding Code 93 character.

The K check is computed in the same way but includes the C check character as the rightmost element in the data string before weighting. Weights for K cycle from 1 through 15 right-to-left. The K character follows the C character in the encoded symbol.

This generator calculates both check characters automatically. You do not need to compute or append them manually.

Comparison with Code 39 structure

Code 39 represents each character with 9 elements (5 bars, 4 spaces) where exactly 3 elements are wide. Code 93 represents each character with 9 modules (3 bars, 3 spaces) without separate wide and narrow elements — the module values are encoded differently. Code 93's structure eliminates the intercharacter gap present in Code 39 (Code 39 is discrete; Code 93 is continuous), which contributes to the density improvement.

When to use a Code 93 barcode

Canada Post delivery information. Canada Post uses Code 93 to encode supplementary delivery information on domestic mail items. This is the most widely cited active deployment of Code 93 in North America. If you are integrating with Canada Post parcel or mail systems and that system specifies Code 93, use Code 93.

Legacy inventory systems requiring Code 93 explicitly. Some warehouse management systems and ERP integrations installed before Code 128 became dominant were set up with Code 93 scanners and label printers configured to that symbology. If the system cannot be reconfigured and already uses Code 93, maintain Code 93 for label continuity.

Developer testing and compatibility verification. Developers building scanning applications that must support historical Code 93 data — from older barcode databases or archival records — can use this generator to produce test symbols for scanner and software integration testing.

When NOT to use Code 93. For any new labelling system, Code 128 is the better choice. Code 128 has a published ISO/IEC standard (ISO/IEC 15417:2007), is the industry default for warehouse and logistics applications, encodes the full ASCII set including lowercase letters without shift sequences, and is universally supported by barcode scanners without requiring explicit enable. Many scanners do not have Code 93 enabled by default.

Print requirements for Code 93

X-dimension. Use the largest X-dimension your label space and scanner resolution allow. Code 93 is continuous, so the module width directly determines the symbol's physical length.

Quiet zones. Code 93 requires a minimum quiet zone on each side of the symbol. The specific requirement follows general linear barcode practice — typically 10X minimum on each end. Any element that encroaches on the quiet zone will prevent the scanner from detecting the start or stop character.

Bar height. Apply the same rule as other linear barcodes: bar height should be at least 15 percent of the symbol length or 5 mm, whichever is greater. Tall bars tolerate scanner tilt better than short bars.

Scanner configuration. This is the most important practical requirement for Code 93: most handheld barcode scanners do not enable Code 93 decoding by default. Before deploying Code 93 labels, check the scanner manual for a Code 93 enable sequence and scan that configuration barcode. A scanner that has not been configured for Code 93 will not decode the symbol even if the print quality is perfect. This is a common cause of failed Code 93 deployments.

Print contrast. Same requirements as any linear barcode: dark bars on a light background. Thermal print calibration matters for the narrower modules in Code 93 relative to Code 39.

Troubleshooting: why your Code 93 barcode is not scanning

Scanner not configured to read Code 93. This is the most common cause of failure. Code 93 is disabled by default on many handheld and fixed-mount scanners. Find the Code 93 enable configuration barcode in the scanner's programming manual and scan it before testing.

Invalid character in the data. The native Code 93 character set includes 43 characters: uppercase A–Z, digits 0–9, space, and the seven special characters -, ., $, /, +, %. Lowercase letters, accented characters and other special symbols require shift encoding. If the generator rejects input, check that the characters are within the supported set.

Check character error. If a Code 93 symbol was produced by a system that computed check digits incorrectly, most scanners will reject it outright. Use this generator to produce a fresh, correctly calculated symbol and compare.

Quiet zone violated. A border, adjacent label element or cropped print margin that cuts into the quiet zone prevents start/stop detection. Maintain at least 10X of clear space on both ends.

X-dimension too small. Code 93 at fine X-dimensions requires higher scanner resolution than Code 39 for the same data. If a symbol that prints cleanly fails to scan, try increasing the X-dimension.

Bidirectional decode issues. Code 93 decodes bidirectionally, but some scanner firmware implementations have known issues with specific patterns read in reverse. Try presenting the label in a consistent orientation.

Code 93 versus Code 128

Code 93 and Code 128 serve similar purposes — alphanumeric variable-length linear barcodes — but they differ in standardisation, character coverage and industry adoption.

Code 93 is approximately 25 percent denser than Code 39, which was its original design advantage. Against Code 128, Code 93 has no meaningful density advantage: Code 128 in Code Set C is denser than Code 93 for numeric data, and Code 128 in Code Set B matches Code 93 for alphanumeric data while offering lowercase support and a published standard.