A1Z26 cipher — turn letters into 1–26 and back

How to use the A1Z26 cipher tool

1. Choose the Direction: Letters → numbers or Numbers → letters.
2. Type into Your text. When decoding, separate the numbers inside a word with dashes, dots or commas, and separate words with a space or a slash.
3. Read the Result. Encoded words are separated by single spaces; decoded text comes out in capital letters.

What it does and when to use it

A1Z26 is the plainest number code there is: each letter becomes its position in the English alphabet. Puzzle setters like it because it needs no key and anyone can check it by counting on their fingers. You will find it in escape rooms, treasure hunts, children’s spy kits and the hidden messages in some TV series.

It is not secure in any sense. Treat it as a way to dress up a message, not to hide it. If a puzzle needs a second layer, people often shift the letters first with the Caesar cipher or mix them with the affine cipher, then write the result in A1Z26. For a grid-based number code, see the Polybius square, and for computer character numbers, where A is 65, see text to ASCII codes.

How it works

Encoding. The text is split into words at spaces and line breaks. In each word the tool converts letters to capitals, removes anything that is not A to Z, and writes each letter’s position: A = 1 up to Z = 26. The numbers of one word are joined with dashes, and words with a single space.

Decoding. Words are split at spaces, line breaks and slashes. Inside a word every run of digits is one number, and any non-digit (dash, dot, comma) separates numbers. Numbers 1 to 26 become letters A to Z; anything else becomes a question mark. Everything happens in your browser.

Worked examples

Results from the tool:

Hello world                       →  8-5-12-12-15 23-15-18-12-4
Meet at 7, Café Zed!              →  13-5-5-20 1-20 3-1-6 26-5-4
9.12.15.22.5 27        (decode)   →  ILOVE ?

The second line shows what gets dropped: the 7 and its comma vanish, the é in Café is removed, and the exclamation mark is lost. In the third line dots work as separators inside the first word, but 27 is outside the alphabet and comes back as a question mark.

Limits and tips

• Capital and small letters give the same numbers, so case is lost.
• Some puzzles use the reverse code, Z = 1 to A = 26. This tool uses A = 1 only; to get the reverse, first run the text through the Atbash cipher, which swaps A with Z, then encode it here.
• If a number puzzle has no separators at all, try reading it with spaces in different places by hand; the tool will not guess where words split.