Polybius square
Encode a message with a 5×5 grid and coordinates.
Turn text into Polybius square coordinates, or decode digit pairs with a classic I/J grid.
Settings
Conversion direction
Coordinate order
Separator
Source text / code
0 source char.
Result
Add source text or code.
Polybius grid
Classic 5×5 grid with I/J in the same cell.
Quick explanation
Choose the conversion direction, row-column or column-row order, then enter your text or coordinates. The reference grid stays visible for checking each letter.
Try this too
Want a tap-based version?
Tap code uses the Polybius-square idea, but turns coordinates into dots or tap sequences.
Additional information
The Polybius square: a coordinate grid
The Polybius square maps each letter to a position in a 5×5 grid. In the classic version, I and J share one cell so the 26 letters fit into 25 positions.
Principle
Each letter becomes two digits: the row number and the column number. In the classic grid, S is row 4, column 3, so it becomes 43.
Historical use
The idea is associated with the Greek historian Polybius, who described a way to transmit letters by coordinates, especially with visual signals.
Difference from tap code
The Polybius square mainly outputs written coordinates. Tap code transmits those coordinates as taps or dots.
| Letter | Coordinate | Reading |
|---|---|---|
| A | 11 | Row 1, column 1 |
| I/J | 24 | I and J share the same cell |
| S | 43 | Row 4, column 3 |
Which tool should you choose?
Use the Polybius square when you want numbers, coordinates, and a visible grid. Use Tap code when you want a rhythmic version that represents letters with taps, dots, or pauses. To learn more, see the Wikipedia page about the Polybius square.
Limits and reuse
AppErgo tools are provided free of charge for practical and informational purposes. Although care is taken in their design, a result may be incomplete, unexpected or incorrect. Before relying on a result for any important use, check it using an appropriate method.
To report a bug in the tool, you can use the dedicated bug report form.
Results produced by AppErgo tools may be copied and reused freely. When publicly reusing a result, a method or an AppErgo page, a link to the relevant page is appreciated.
Unless otherwise stated, AppErgo texts, images, visual elements, scripts, templates and internal components remain the property of AppErgo.
For any other request, you can contact the webmaster.