Introduction
Need to turn a word into its alphabetical position numbers? The A=1, B=2 system maps each letter to its spot in the alphabet: A becomes 1, B becomes 2, Z becomes 26. It shows up in escape rooms, geocache puzzles, classroom exercises, and CTF warmup challenges. This tool converts your text in three systems at once: alphabetical positions, ITU-T E.161 phone keypad digits, and ASCII decimal codes. Paste your text below and copy whichever format your puzzle needs. Everything runs in your browser.
What this tool does
- Converts each letter to its alphabetical position number (A=1, B=2, through Z=26) with your choice of separator.
- Maps letters to phone keypad digits per ITU-T E.161: 2 holds ABC, 3 holds DEF, through 9 for WXYZ.
- Outputs ASCII decimal values for every character including symbols and spaces, covering codes 0 through 127.
- Handles uppercase and lowercase input identically, since A=1 and a=1 produce the same number.
- Lets you encode spaces as 0 so word boundaries survive the round trip through numbers to letters decoding.
How this tool works
The tool reads your input string character by character and runs three independent conversions. For A=1 B=2 output, each letter is converted to its character code minus 64 (uppercase) or 96 (lowercase), yielding 1 through 26. Digits pass through unchanged. Spaces become 0 when that option is enabled, or are skipped entirely.
For phone keypad output, each letter is looked up in the ITU-T E.161 mapping table. The digit 2 covers ABC, 3 covers DEF, 4 covers GHI, 5 covers JKL, 6 covers MNO, 7 covers PQRS, 8 covers TUV, and 9 covers WXYZ. The digits 1 and 0 have no letters assigned. This mapping is the same one used by T9 predictive text on legacy mobile phones.
For ASCII output, each character is converted to its decimal code point. The space character is code 32, uppercase A is 65, lowercase a is 97. ASCII covers 128 codes total, defined by ANSI X3.4-1986 and now maintained as ISO/IEC 646.
All three results update as you type. You can switch between hyphen, space, comma, period, or no separator. The output is plain text that you can copy with one click.
How the cipher or encoding works
The A=1 B=2 system is a positional numeral mapping, not a cipher in the cryptographic sense. It assigns each of the 26 Latin letters a number from 1 to 26 based on its position in the alphabet. The system is sometimes called A1Z26 in puzzle communities. It provides no security: the mapping is fixed and publicly known. Its value is educational and recreational.
Phone keypad encoding follows ITU-T E.161, the international standard that defines the arrangement of digits and letters on telephone keypads. The standard was first published in 1988 and updated in 2001. The letter-to-digit assignment existed on American telephones since the 1930s for exchange names like PEnnsylvania 6-5000. Q and Z were not part of the original layout. They were added later when mobile phone texting required a complete alphabet, with Q landing on 7 (PQRS) and Z on 9 (WXYZ).
ASCII, the American Standard Code for Information Interchange, was published as ANSI X3.4 in 1963 and last revised in 1986. It assigns decimal codes 0 through 127 to control characters, digits, letters, and symbols. Uppercase A through Z occupy codes 65 through 90. Lowercase a through z occupy 97 through 122. The difference between uppercase and lowercase for the same letter is always 32, which comes from bit 5 being set for lowercase.
These three systems serve different purposes. A=1 B=2 is compact and human-readable for short puzzles. Phone keypad encoding matches real telephone interfaces but loses information because multiple letters map to the same digit. ASCII is complete and unambiguous but produces long number sequences. For decoding numbers back to text, use the dedicated numbers to letters tool.
How to use this tool
- Type or paste your text into the input field above.
- Pick a separator from the dropdown: hyphen, space, comma, period, or none.
- Tick the "Encode spaces as 0" box if you need word boundaries preserved for round-trip decoding.
- Review the three output panels: A=1 B=2, phone keypad, and ASCII decimal.
- Click the copy icon next to the result you need. Paste it into your puzzle, document, or numbers to letters decoder.
Real-world examples
Geocache puzzle with A=1 B=2 coordinates
A geocache description gives the clue "20-8-5 18-15-3-11" and asks you to find the cache name. You type "THE ROCK" into the letters to numbers tool and confirm the A=1 B=2 output matches: 20-8-5 18-15-3-11. The match validates your answer before you submit it.
Creating a vanity phone number
A plumber wants to check if their business number 1-800-466-3278 spells anything memorable. They type common plumbing words into the tool and check the phone keypad output. "HOME" produces 4-6-6-3, "GOOD" produces 4-6-6-3, and "INFO" produces 4-6-3-6. None match 466-3278 exactly, but the tool lets them test dozens of candidates in seconds.
CTF challenge encoding a flag
A CTF challenge author needs to encode the flag "FLAG{NUMBERS}" as a series of ASCII decimal values to make the challenge harder. They paste the flag into the tool and get the ASCII output: 70-76-65-71-123-78-85-77-66-69-82-83-125. Participants must recognize these as ASCII codes and use a numbers to letters decoder to recover the flag.
Comparison with similar methods
| Method | Complexity | Typical use |
|---|---|---|
| A=1, B=2 (A1Z26) | O(n) lookup, no key | Escape rooms, geocaches, classroom puzzles |
| Phone keypad (E.161) | O(n) lookup, lossy | Vanity numbers, T9 texting, telecom puzzles |
| ASCII decimal | O(n) code point, lossless | Programming, CTF challenges, data representation |
Limitations or considerations
A=1 B=2 only handles the 26 Latin letters. Accented characters like é or ñ, Cyrillic, CJK, and other scripts are skipped. Phone keypad encoding is lossy: ABC all become 2, so you cannot reverse it without context. ASCII handles 128 characters but produces long output for short input. The word "HELLO" becomes 72-69-76-76-79 in ASCII, which is harder to transcribe than 8-5-12-12-15 in A=1 B=2. For decoding numbers back to text, switch to the numbers to letters tool.
Frequently asked questions
What number does each letter become in A=1, B=2?
A is 1, B is 2, C is 3, and so on through Z at 26. The number equals the letter's position in the alphabet. Uppercase and lowercase produce the same number: both A and a become 1.
How do I convert letters to phone keypad numbers?
The mapping follows ITU-T E.161: ABC=2, DEF=3, GHI=4, JKL=5, MNO=6, PQRS=7, TUV=8, WXYZ=9. The digits 1 and 0 have no letters. This tool applies the mapping automatically when you select the phone keypad output.
Can I decode the numbers back to letters?
Yes, but only for A=1 B=2 and ASCII. Phone keypad encoding is lossy because multiple letters share one digit. Use the numbers to letters tool for the reverse direction. It accepts any separator: hyphens, spaces, commas, or periods.
What separator should I use?
Hyphens are the most common choice for puzzles because they are easy to read. Commas work well for data formats. No separator produces the most compact output but makes decoding harder if the numbers are two digits. Spaces are a middle ground.
Why does ASCII produce bigger numbers than A=1 B=2?
ASCII assigns codes 65 through 90 to uppercase letters, while A=1 B=2 uses 1 through 26. ASCII covers all 128 standard characters including symbols and control codes, so it needs a wider number range. A=1 B=2 only covers the 26 letters.
Conclusion
Letters to numbers conversion is a quick building block for puzzles, CTF challenges, and educational exercises. The tool gives you three encodings in one pass so you do not need to guess which one your puzzle uses. When you need to go the other direction, open the numbers to letters tool.