🔢 A1Z26 Cipher
Convert letters to numbers (A=1, B=2, ..., Z=26) and back. Choose your separator: hyphen, space, or comma.
About the A1Z26 Cipher
The A1Z26 cipher (also called the letter-to-number cipher) replaces each letter of the alphabet with its position: A=1, B=2, ..., Z=26. It is one of the simplest substitution schemes and a common entry point for learning cryptography. This tool runs entirely in your browser — nothing is uploaded.
How it works
- Letters to Numbers — Each letter A–Z (case-insensitive) is replaced by its position 1–26. Numbers are joined by the chosen separator.
- Numbers to Letters — Sequences of digits are parsed as numbers and converted back to letters (1=A, 2=B, ..., 26=Z).
- You can pick the separator used between numbers: hyphen (
-), space, or comma (,). - Non-alphabetic characters in encode mode (punctuation, digits in the source) are passed through unchanged. In decode mode, anything that is not a number or the chosen separator is left untouched.
Use cases
- Beginner cryptography exercises and classroom puzzles.
- Creating simple scavenger-hunt or escape-room clues.
- Hiding mild spoilers or punchlines in casual chat.
- Building blocks for more complex ciphers (e.g. combined with Caesar shift).
Frequently asked questions
Is A1Z26 secure? No. It is a direct, keyless substitution and is trivially reversed. Use it for fun and learning, not for protecting secrets.
What happens to lowercase letters? The tool is case-insensitive when encoding. When decoding, the output is uppercase by default.
What if I have numbers larger than 26? When decoding, numbers outside 1–26 are kept as-is so you can spot mistakes.
Does this tool upload my text? No. All conversion happens locally in your browser.