Polybius square encoder
The Polybius square is an ancient Greek way to turn letters into digits, seen in puzzles and the prison tap code. It is a puzzle cipher, not protection.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter text.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Square rows: ABCDE / FGHIK / LMNOP / QRSTU / VWXYZ. Code = row number then column number, so H = 23, and J = 24 like I.
Example
Result: Encoded text: 23 15 31 31 34 / 52 34 42 31 14; Letters processed: 10.
Hello world
23 15 31 31 34 / 52 34 42 31 14
Limits and caveats
- This is a puzzle and teaching cipher that is easy to break, so never use it to protect passwords or sensitive data.
- I and J share code 24, digits and symbols are dropped, and words are separated by /.
Questions about this tool
Why do I and J share a code?
The 5×5 square has only 25 cells, so J is merged with I by convention.
Is the first digit the row or the column?
The first digit is the row and the second the column, which is the most common order.
How does it relate to the tap code?
The tap code uses a similar square: you tap the row number, pause, then tap the column number.