Free Online Tool
Polybius Square
Convert text using the ancient Polybius square cipher with a 5x5 grid substitution method.
How to Use Polybius Square
- Enter text and select Encode.
- Each letter is looked up in the fixed 5×5 square; J shares I’s cell.
- Read row then column as a two-digit coordinate, with spaces inserted between every input character.
- Select Decode to extract digit pairs and map them back to letters.
A Polybius square replaces letters with coordinates. This component uses A–E in row 1 through V–Z in row 5, combining I/J at 24.
Examples
Fixed square — input:
HELLO
Output:
23 15 31 31 34
J shares coordinate 24 with I — input:
JAZZ
Output:
24 11 55 55
Features
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