Baudot / ITA2 Code Decoder

Encode and decode text using 5-bit ITA2 teletype code and visualize the output as punched paper tape.

Last reviewed: April 2026
Reviewed by , software engineer · last updated April 2026

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Plain Text
ITA2 Bit Codes (5-bit groups)
Enter text to encode to Baudot ITA2.

How to Use the Baudot / ITA2 Decoder

To encode text, enter your plain text into the designated input area. The tool will convert it into 5-bit ITA2 code groups, automatically inserting Letters Shift and Figures Shift codes as necessary. To decode, paste space-separated 5-bit ITA2 groups into the input, and the tool will translate them back into readable text.

Beyond encoding and decoding, this tool can visualize your input as a punched paper tape diagram. Each row on the tape represents a character, with holes indicating '1' bits and unpunched positions indicating '0' bits across the five data channels.

Understanding Baudot / ITA2 Code

Baudot code, specifically its International Telegraph Alphabet No. 2 (ITA2) variant, is a 5-bit character encoding system. This means each character is represented by a unique sequence of five binary bits. Due to the limited number of combinations (32), ITA2 uses special 'shift' codes-Letters Shift and Figures Shift-to switch between two different character sets, allowing for more than 32 characters to be represented.

This encoding was widely used in teletypewriters, teleprinters, and early telecommunications systems. Its applications included TTY/TDD devices, amateur radio RTTY transmissions, and some older naval and maritime signaling. The decoder helps users understand and work with these historical communication methods.

Practical Applications and Considerations

While largely superseded by ASCII in modern computing since the 1960s, Baudot / ITA2 code remains relevant for specific legacy systems and historical studies. It is valuable for those maintaining older equipment, engaging in amateur radio, or learning about the evolution of character encoding.

This tool processes all encoding and decoding operations directly in your browser. This client-side approach ensures that your data remains private and is not transmitted to a server. Users should note that the 5-bit nature of ITA2 means it does not support the full range of characters found in modern encodings like Unicode.

Frequently Asked Questions

Baudot code is a 5-bit character encoding system developed by Émile Baudot in 1870. It was designed for telegraph and teletype machines, representing each character with five binary bits.
Due to its 5-bit nature, Baudot (ITA2) uses 'Letters Shift' (code 11111) and 'Figures Shift' (code 11011) to switch between two character sets. This allows the system to represent more than 32 unique characters, including both alphabetic and numeric/symbol characters.
ITA2 (International Telegraph Alphabet No. 2) is the internationally standardized version of Baudot code. Adopted by the ITU in 1932, it became the primary standard for international telex systems throughout much of the 20th century.
Baudot paper tape features five data channels running across its width, corresponding to the five bits of each character. A smaller sprocket hole column is present for tape transport. A punched hole signifies a '1' bit, while an unpunched position indicates a '0' bit.
While largely replaced by modern encodings, Baudot code is still found in specific legacy applications. These include TTY/TDD telecommunications devices, amateur radio RTTY transmissions, and certain older naval and maritime signaling systems.