About Code 25 (Standard 2 of 5) Barcodes
Code 2 of 5 (commonly known as Standard 2 of 5, or Code 25 Industrial) is a legacy, numeric-only 1D linear barcode symbology developed in the late 1960s. It is a discrete barcode where each character is separated by a fixed space. The name "2 of 5" stems from the fact that each numeric character is represented by a group of five bars, exactly two of which are wide, while the spaces between the bars are of constant width and do not carry data.
How Code 25 (Standard 2 of 5) Encoding Works
Code 2 of 5 encodes digits 0-9. Each digit is represented by 5 bars, with 2 wide bars and 3 narrow bars. The spaces between the bars are narrow and contain no information. It starts with a simple start pattern, followed by the encoded data, and ends with a stop pattern. Because the spaces do not carry data, Code 2 of 5 has a low data density, requiring more physical space than its interleaved counterpart (Interleaved 2 of 5), which encodes digits in both bars and spaces.
Common Applications and Industries
Code 2 of 5 was historically used in warehouse sorting, heavy industry, airline ticketing (ticketing and baggage tracking), and photofinishing labs. Today, it has been largely superseded by Interleaved 2 of 5 (ITF) and Code 128 due to their superior data density and lower error rates. However, Code 2 of 5 is still maintained in legacy systems and industrial databases.
Advantages & Limitations
The main advantage of Code 2 of 5 is its simplicity and easy readability by early optical scanners. Because the spaces do not carry information, it is highly tolerant of printing defects. The main disadvantage is its extremely low density, resulting in very long barcodes for even short digit strings. It also lacks a built-in checksum, making it susceptible to misreads if not configured with software filters.