Skip to main content
Book Consultation →
Substitution ciphers100% FreeInstant

A1Z26 Cipher: Letters to Numbers and Back

This free A1Z26 cipher tool replaces each letter with its place in the alphabet, so A is 1 and Z is 26. It also turns a list of numbers back into letters, with a separator you choose.

By Debmedia Technologies LLP · Kolkata, India · Updated

What Is It and When Do You Need It?

A1Z26 maps every letter to its position in the alphabet. It is the code most people invent as children, and it still appears in puzzle hunts, escape rooms and geocaches.

Choose the direction and paste your text or numbers.

How to Use This Tool

  1. Type letters or numbers.
  2. Choose the direction.
  3. Choose the separator.
  4. Press Run and copy the result.

How the Calculation Works

A letter is converted to number = letter − A + 1. A slash is used between words when encoding. When decoding, numbers from 1 to 26 are turned back into letters, and a slash becomes a space.

Worked Example

HELLO WORLD becomes 8 5 12 12 15 / 23 15 18 12 4. The numbers 3 1 20 decode to CAT.

Common Uses

  • Puzzle hunts.
  • Escape rooms.
  • Kids’ codes.
  • Geocaching.

Tips and Common Mistakes

  • Use dashes if the numbers are hard to read.
  • Numbers above 26 are reported as errors.
  • Combine with the Caesar cipher for harder puzzles.
  • To make a puzzle harder, shift the numbers first, for example add 3 to every number, so that readers need two steps to decode the message.
  • Remember that the code only covers the letters A to Z, so numbers and punctuation in your message are dropped when you encode.

Next, you may need the Caesar cipher, Polybius square, Bacon cipher, NATO alphabet.

Everything runs in your browser. Nothing you type is uploaded, stored or sent to any outside service.

Frequently Asked Questions

The simplest letter-to-number code: A is 1, B is 2, up to Z which is 26.
In letters-to-numbers mode, a slash marks the space between words so you can tell where words end.
It is a code, not a secure cipher. There is no key, so anyone can decode it.
Puzzles, escape rooms, children’s games and geocaching.

Disclaimer: results are calculated in your browser from the numbers you enter. Check important results before you rely on them for money, health, safety or legal decisions.