How this instrument works
A1Z26 is the simplest possible letter-substitution scheme: replace each letter with its position in the standard 26-letter Latin alphabet, so A becomes 1, B becomes 2, and so on down to Z at 26. The name literally describes the two endpoints of the mapping — A is 1, Z is 26. There's no key, no shifting, and no configuration involved; the mapping is completely fixed and the same for everyone.
Because it's so simple and fully public, A1Z26 shows up constantly in puzzle hunts, geocaching clues, escape rooms, and classroom introductions to cryptography, where it serves as a first, gentle example of turning letters into numbers before moving on to schemes that actually hide information. It offers no real security whatsoever — anyone who recognizes the pattern (letters mapping to small integers between 1 and 26) can decode it instantly without any special tool, which is exactly why it's used for light puzzles rather than anything meant to stay hidden.
This instrument converts one letter at a time, selected from a dropdown, rather than accepting a whole typed word or sentence. To convert a full word, look up each of its letters individually, in order, and read the resulting numbers off as a sequence — for example, converting the word 'CAB' means looking up C (3), then A (1), then B (2), giving the sequence 3, 1, 2.
- Select Letter from the dropdown (A through Z).
- Read Number for that letter's position in the alphabet.
- To convert a whole word, repeat this for each letter in order and write down the resulting numbers in sequence.
- Use this site's companion Numbers to Letters instrument to convert the reverse direction, from a number back to a letter.
Worked example — converting the word CAB, letter by letter
To convert the word 'CAB' using this instrument, look up each letter in turn. Selecting C returns Number = 3 (the third letter of the alphabet). Selecting A returns Number = 1, matching this tool's own default state — A is the very first letter, so it maps to 1.
Selecting B returns Number = 2. Reading the three results back in the original word order gives the sequence 3, 1, 2 — the A1Z26 encoding of 'CAB', exactly the kind of number sequence you'd see in a geocaching clue or puzzle-hunt cipher built on this scheme.
Questions
What is the A1Z26 cipher?
It's the simplest letter-to-number substitution scheme: each letter of the alphabet is replaced by its position within it, so A=1, B=2, C=3, and so on through Z=26. There's no secret key involved — the mapping is fixed and identical for everyone, which is why A1Z26 is used mainly for light puzzles, geocaching clues, and teaching the basic idea of substitution ciphers rather than for anything requiring real secrecy.
Does this tool convert a whole word or sentence at once?
No — it converts one selected letter at a time via a dropdown. To encode a full word, look up each of its letters individually, in the order they appear, and write down the resulting numbers as a sequence. For example, encoding 'CAB' means looking up C, A, and B in turn, giving the sequence 3, 1, 2.
Is A1Z26 actually secure encryption?
No, not remotely. Because the mapping from letter to number is fixed, public, and has no key at all, anyone who recognizes the pattern of small integers between 1 and 26 can decode an A1Z26 message instantly, without any tool or calculation beyond counting through the alphabet. It's used for casual puzzles, geocaching clues, and cryptography teaching examples specifically because it's easy to both create and break — not as a way to genuinely protect information.
What number corresponds to the letter Z?
26 — Z is the last letter of the 26-letter Latin alphabet, so under the A1Z26 cipher's straightforward position-in-the-alphabet mapping, it always converts to the number 26, the highest number the cipher ever produces for a single letter.
How do I convert a number back into a letter?
Use this site's companion Numbers to Letters instrument, which applies the exact same A1Z26 mapping in reverse: enter a number from 1 to 26 and it returns the matching letter, so entering 3 returns C, entering 1 returns A, and so on, mirroring this tool's letter-to-number direction exactly.