Letter to Number Cipher (A1Z26) — A=1 to Z=26

How A1Z26 works

A1Z26 — named after its first and last pairs — is the simplest letter-to-number code: each letter becomes its position in the English alphabet, from A = 1 to Z = 26. It is a favourite in escape rooms, scavenger hunts, geocaching and classroom puzzles because anyone can decode it with the alphabet written out.

Separators and word breaks

Numbers must be separated, or the message becomes ambiguous — “121” could be ABA, LA or AU. Choose the separator your puzzle uses:

With dashes, commas or dots between letters, a plain space marks a new word. With spaces between letters, a slash marks the word break. When decoding, the tool works out which separator a line uses, so you can paste any of these formats (including “8, 5, 12” with spaces after the commas). Punctuation such as commas and apostrophes between words is kept.

Worked example: CODE

C is the 3rd letter, O the 15th, D the 4th and E the 5th, so CODE is 3-15-4-5. To decode, write the alphabet with numbers underneath and look each number up. A quick self-check for puzzles: the numbers of CODE add up to 27, and checksums like this are sometimes used as an extra clue.

Variations you may meet

• Zero-based (A = 0 … Z = 25): used in programming and in cipher arithmetic (the Caesar and Vigenère ciphers count from A = 0). Subtract one from each A1Z26 number.
• Reversed (A = 26 … Z = 1): equivalent to applying the Atbash cipher first. For example, Atbash then A1Z26 turns CODE into 24-12-23-22.
• Shifted alphabets: combine with a Caesar shift for a harder puzzle — CODE shifted by 1 is DPEF, which is 4-16-5-6.

A1Z26 is a code for fun, not security: with only 26 values and no key, anyone can read it. For a printable letter reference in other systems, see the Morse alphabet or the NATO phonetic alphabet.

Decoding tips

• Numbers above 26 mean the puzzle is not plain A1Z26 — try A1Z26 after subtracting 26, or a different code such as ASCII (where A = 65).
• Leading zeros such as 08-05-12 are fine; they keep every number two digits long and are read normally.
• No separators at all? Look for 1s and 2s followed by another digit: they may be the start of a two-digit letter (10–26). Try the readings that give real words.

Common words in A1Z26

The sum column is a popular extra puzzle mechanic — for example, a lock code made from the total of a word’s letters. Because many different words share the same total, a sum alone can never be decoded back to one word, which is why it works as a check rather than a cipher.

Quick mental lookup

Memorising a few landmarks makes decoding much faster than counting from A every time:

From there, count forwards or backwards a step or two: 14 is one after M (13), so N; 19 is one before T (20), so S. With practice, short messages decode almost as fast as reading.

Make your own puzzle

1. Write a short message and type it into the Letters box.
2. Pick a separator; dashes are the easiest for players to read.
3. For a harder layer, encode the message with the Caesar cipher or Atbash first, then convert the result to numbers.
4. Use Copy share link to save a link to your exact puzzle and settings.