Polybius Square Cipher
Encode letters as row-and-column coordinates using the classic 5x5 Polybius square.
Input
Output
Using This Tool: Guide & Notes Show guide
The Polybius square turns letters into row-and-column coordinates from a 5x5 grid.
How to use it
- Choose Encode to turn letters into coordinates, or Decode to reverse coordinates into letters.
- Paste text or coordinate pairs into the input box.
- Use the square display to check where each letter sits.
- Copy the output once the coordinate format looks right.
Options and settings
- The square controls every mapping, so keyword or alphabet changes alter the coordinate output.
- I/J handling matters because a 5x5 square has only 25 cells.
- Separators make coordinate pairs readable and easier to decode.
- Grouping can make long coordinate streams easier to scan.
Notes
- Polybius is often used as a first stage in stronger classical systems.
- Coordinates are not secure by themselves; the grid is easy to reconstruct.
Related Article
Polybius Square Cipher guide coming soon
The matching article is not published yet. This tool is ready now, and the guide can be added through the shared article template when it is written.