A1Z26 Cipher
Convert letters to numbers and back — A=1, B=2, all the way to Z=26.
How to Use A1Z26 Cipher
- Choose Text → Numbers to encode or Numbers → Text to decode.
- Type or paste your text or number sequence into the input box.
- Pick the numbering (standard, zero-indexed or reverse) and, when encoding, the separator between letters. The result updates instantly; in the standard numbering each letter maps to its alphabet position (A=1 … Z=26).
- Use Copy to grab the result. Everything runs in your browser — nothing is uploaded.
What this tool does
A1Z26 replaces each letter with its place in the alphabet. This page is the converter: it handles the standard numbering plus the zero-indexed and reverse variants, keeps word breaks, and lists every way an unseparated run of digits can be read. For the background, the full A–Z table and a hand-worked method, read the A1Z26 cipher guide.
Worked Examples (real output of this tool)
Every result below is computed by the same code as the converter above and checked by tests. The inputs are examples chosen to show behaviour, not real messages.
Encode a phrase: HELLO WORLD
Input:
HELLO WORLD
Output:
8-5-12-12-15 23-15-18-12-4
Letters inside a word are joined by the separator; the space between words is kept.
Decode numbers: 3-1-20
Input:
3-1-20
Output:
CAT
Each number is read as a letter position: 3 = C, 1 = A, 20 = T.
Slash between words: 8-9 / 20-8-5-18-5
Input:
8-9 / 20-8-5-18-5
Output:
HI THERE
A slash (or whitespace) is read as a word break, so the decoded text keeps its spacing.
Zero-indexed variant (A=0): HELLO
Input:
HELLO
Output:
7-4-11-11-14
Every number is one lower than in the standard cipher. Z becomes 25 and 26 is out of range.
Reverse variant (A=26, Z=1): HELLO
Input:
HELLO
Output:
19-22-15-15-12
The numbering runs backwards, so the number for each letter is 27 minus its standard number.
Numbers outside 1-26: 0-27-5
Input:
0-27-5
Output:
??E
In the standard cipher only 1-26 are letters. 0 and 27 have no letter, so they decode to ?.
Punctuation passes through: Hello, World!
Input:
Hello, World!
Output:
8-5-12-12-15-, 23-15-18-12-4-!
Non-letters are not numbered. They stay in place and are still joined to the previous letter by the separator.
Without separators: 1215
Input:
1215
Output:
?
The decoder splits on non-digits, so the unseparated run 1215 is one number, 1215, which is out of range. The checker below lists the five valid readings of these four digits.
Unseparated digits: how many readings?
Numbers 1–9 have one digit and 10–26 have two, so a run of digits without separators can be split in more than one valid way. The counts below are computed by this tool for the standard numbering (hypothetical digit strings, not real messages). The converter treats an unseparated run as a single number; type one into Numbers → Text to see its readings listed.
| Digits | Valid readings | Readings (first 6) |
|---|---|---|
| 19 | 2 | AI, S |
| 111 | 3 | AAA, AK, KA |
| 1215 | 5 | ABAE, ABO, AUE, LAE, LO |
| 2626 | 4 | BFBF, BFZ, ZBF, ZZ |
| 8512121523 | 26 | HEABABAEBC, HEABABAEW, HEABABOBC, HEABABOW, HEABAUEBC, HEABAUEW |
A separator (hyphen, comma or space) between numbers is what removes the ambiguity. See the guide for the puzzle-solving side of this.
A1Z26 Cipher FAQ
How do I convert letters to numbers with A1Z26?
Replace each letter with its position in the alphabet: A=1, B=2, up to Z=26. For example HELLO becomes 8-5-12-12-15. In this tool choose Text to Numbers and type the text; spaces between words are kept.
How do I decode numbers back to letters?
Choose Numbers to Text and enter numbers separated by hyphens, commas or spaces. 3-1-20 decodes to CAT. Numbers outside 1-26 have no letter in the standard cipher and decode to a question mark.
Why does 1215 have more than one reading?
Without separators the digits can be split into one- and two-digit numbers in several valid ways. 1215 can be read as 12-15 (LO), 12-1-5 (LAE), 1-21-5 (AUE), 1-2-15 (ABO) or 1-2-1-5 (ABAE): five readings. The decoder in this tool splits on non-digits, so it treats an unseparated run as a single number; use the reading checker to list every split.
How many readings can an unseparated digit string have?
It depends on the digits. The string 1111111111 can be split into one- and two-digit numbers 89 ways, because the counts follow the Fibonacci numbers. Digits such as 0, or two-digit pairs above 26, remove some splits. 07 has no valid reading at all, because a leading zero is not allowed.
What happens to punctuation and numbers in the text?
When encoding, only the letters A-Z are numbered. Punctuation and digits pass through unchanged and are still joined to the previous letter by the separator, so Hello, World! becomes 8-5-12-12-15-, 23-15-18-12-4-!. Accented letters are not part of the 26-letter alphabet and also pass through.
Can I use a space as the separator between letters?
You can, but word breaks are lost. With a space between letters, HI THERE encodes to 8 9 20 8 5 18 5, and decoding that gives H I T H E R E, because a space is also read as a word break. Use a hyphen or comma between letters and a space or slash between words.
What are the zero-indexed and reverse variants?
Zero-indexed numbers the alphabet A=0 to Z=25, so HELLO is 7-4-11-11-14. The reverse variant numbers it backwards, A=26 to Z=1, so HELLO is 19-22-15-15-12. Pick the variant in the tool; always confirm which numbering a puzzle uses.
Is A1Z26 encryption?
No. It is a fixed letter-to-number mapping with no key, so anyone with the alphabet table can reverse it. It is useful for puzzles and learning, not for keeping a message private.
Does the tool send my text anywhere?
No. The conversion runs in your browser; nothing is uploaded.
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