HesapHanem

A1Z26 Cipher (Letter ↔ Number)

Encode letters as numbers or decode numbers back to letters.

How it is calculated

The A1Z26 cipher replaces each letter with its place in the English alphabet: A=1, B=2, … Z=26. In encode mode the engine reads the text word by word. Uppercase and lowercase letters give the same number, and any character that is not an A to Z letter (digits, punctuation, accented or non-Latin letters) is dropped. The numbers of one word are joined by spaces, and the words are joined with / . In decode mode you do the opposite: a slash separates words, whitespace separates numbers, and each number from 1 to 26 becomes a lowercase letter. Numbers outside that range and non-numeric tokens are skipped. Decoded words are separated by a single space, so the output has no capital letters or punctuation.

Worked example

Encode the text "Hello world". The first word is H E L L O: H is the 8th letter, E the 5th, L the 12th (twice) and O the 15th, so it becomes 8 5 12 12 15. The second word is W O R L D: 23, 15, 18, 12, 4. The words are joined with a slash, so the result is 8 5 12 12 15 / 23 15 18 12 4. Pasting that sequence back in decode mode returns "hello world" in lowercase.

Try this example →

Common mistakes

  • Decoding numbers glued together like 85121215. The engine needs spaces between numbers because it cannot tell 1 and 12 from 11 and 2.
  • Writing Turkish letters such as ç, ş or ğ and expecting a number. Only the 26 letters A to Z are encoded; others are silently removed.
  • Using hyphens between numbers when decoding. Separate numbers with spaces and words with a slash.
  • Expecting capital letters or punctuation back after decoding. The case and punctuation of the original are not stored.

About this calculator

This tool converts text with the A1Z26 cipher, a simple substitution scheme that maps each letter to its position in the alphabet — A=1, B=2, ... Z=26 — and back again. Numbers are usually separated by spaces or hyphens (e.g. "HELLO" becomes "8-5-12-12-15").

Puzzle setters, escape-room designers, and students learning about classical ciphers use it to encode hidden messages or as a first step before layering on other ciphers like Caesar or Vigenère.

Was this helpful?

You can pick up to 3 reactions.

Comments (1)

  • Editorial team

    When you decode, put ' / ' between words and plain spaces between numbers; without the slashes everything joins into one word. Any number outside 1 to 26 is silently skipped, so a missing letter in the output usually means a mistyped number. When encoding, digits, punctuation and letters such as ç are dropped. If you work with the 29-letter Turkish alphabet, tell us how you would number it.

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators