Tap Code Translator

About this calculator

Tap code maps the 26-letter alphabet onto a 5×5 Polybius square by combining C and K into one cell, then encodes each letter as a pair of tap groups — one for its row, one for its column (for example, "B" sits at row 1, column 2, so it's tapped as one knock, then two knocks). Converting text runs each letter through that same row-column lookup, and decoding reverses it by counting the taps in each pair.

The code became famous as a way for prisoners of war — most notably American POWs held in Vietnam — to communicate silently through cell walls when spoken language and visible signals weren't possible. Today escape room designers, puzzle hobbyists, and cryptography enthusiasts use tap code translators like this one to build and solve puzzles based on the same historical cipher.