How does the A1Z26 cipher work?

Each letter is replaced by its position in the alphabet: A=1, B=2, through to Z=26. Letters within a word are joined by hyphens and words are separated by spaces.

How do I format text to decode?

Put hyphens between the numbers of a single word and spaces between words — for example, 7-5-18-1 decodes to "gera". Numbers outside 1–26 are passed through unchanged.

Is the A1Z26 cipher case sensitive?

No. Both uppercase and lowercase letters map to the same position, so A and a both become 1. Decoded output is returned in lowercase.

What happens to spaces, digits and punctuation?

Spaces separate words and are preserved. Any character that is not a letter (digits, punctuation) is passed through unchanged when encoding, and any number outside 1–26 is left as-is when decoding.

Is the A1Z26 cipher secure?

No. It is a simple substitution scheme with no key, so anyone who recognises the pattern can decode it instantly. Treat it as a puzzle or a learning exercise, not real encryption.

Where is the A1Z26 cipher used?

It is common in puzzle hunts, escape rooms, geocaching, CTF challenges and classroom cryptography exercises, where numbers like 8-5-12-12-15 stand in for words.

No — the conversion runs entirely in your browser and nothing is sent to a server.

A1Z26 Cipher Encoder & Decoder

The A1Z26 cipher is a basic substitution cipher that swaps every letter for its position in the English alphabet. It is widely used in puzzle games, escape rooms, geocaching, and beginner cryptography lessons because it is easy to learn yet still hides plain text from a casual glance. This free tool encodes text into numbers and decodes numbers back into letters instantly, with no account and no upload.

How it works

Encoding maps each letter to a number from 1 to 26: A=1, B=2, C=3, … Z=26. The mapping is case-insensitive, so A and a both produce 1. Within a single word the numbers are joined with hyphens, and a space separates one word from the next. Any character that is not a letter — a digit, comma, or symbol — passes through unchanged.

Decoding reverses the process. Each hyphen-separated number is converted back to its letter using letter = char(96 + n), producing lowercase output. Numbers outside the 1–26 range, or items that are not whole numbers, are left exactly as typed so nothing is silently lost.

Example

Encode the word GERA:

G is the 7th letter → 7
E is the 5th letter → 5
R is the 18th letter → 18
A is the 1st letter → 1

Joined with hyphens, GERA becomes 7-5-18-1. Decoding 7-5-18-1 returns gera.

Letter	Number	Letter	Number
A	1	N	14
E	5	R	18
G	7	Z	26

Everything runs locally in your browser — your text is never sent to a server.