A1Z26 Cipher
The A1Z26 cipher replaces every letter with its position in the alphabet, so A becomes 1, B becomes 2, and Z becomes 26. Type letters on the left and the numbers appear on the right, joined by the separator you choose below. Use the swap button to switch direction and paste a number sequence to read the letters back out — spaces, dashes, and commas are all accepted, and the tool works out where one word ends and the next begins. A number outside the range 1–26 isn't a letter, so it's left in the output as a number. Everything runs in your browser; nothing you type is ever sent to a server.
How do you decode an A1Z26 cipher by hand?
Read each number as a count into the alphabet: 1 is A, 2 is B, and so on up to 26 for Z.
So 3 15 4 5 reads C, O, D, E, which spells CODE. By hand it's quicker to
work in fives, since 5 is E, 10 is J, 15 is O, 20 is T, and 25 is Y — landmarks
that leave at most four letters to count from. An 18 is three past 15, so it lands on R.
To do it here, click the swap button and paste the numbers into the left panel.
What is A1Z26, and what makes it a letters-to-numbers cipher?
A1Z26 is a name for the plain numbering of the English alphabet, and the name spells out its own rule: A is 1 and Z is 26. Every letter in between takes the number of its place in the alphabet, with no shift, no key, and no rearrangement — which is exactly why it's the most common letters-to-numbers cipher, and reversing it is just as simple a number-to-letter cipher, going the other way. Nothing needs memorizing beyond the alphabet you already know, which is why the cipher is so common in puzzles aimed at people who have never encoded anything before. If you're looking for a cipher that shifts letters instead of numbering them, see the Caesar Cipher tool.
Is A1Z26 the same as Atbash?
No — they're easy to mix up but work in opposite directions. A1Z26 numbers the alphabet in order (A=1…Z=26). Atbash reverses it instead, so A=26 and Z=1, with every letter mapped to its mirror position. To convert an A1Z26 number to its Atbash equivalent, subtract it from 27: a 3 under A1Z26 becomes 24 under Atbash, so it decodes to X rather than C.
What happens to spaces, punctuation, and numbers already in my text?
They're left exactly where they are. Only letters get converted — a comma, an
exclamation point, or a digit already in your input passes straight through to the
output in its original position, so Hi, 2026! becomes
8 9, 2026! rather than trying to re-encode the punctuation or the numeral.
Last reviewed: August 2026