Letters ↔ Numbers Converter
Convert alphabet letters to numbers (A=1) and back. Useful for puzzles, crypto, and teaching.
Mapping
(A..Z)
Non-letters preserved when converting letters→numbers
Features: copy, download, preserve punctuation, custom base (A=0/1)
Handles multi-digit numbers and separators
Letters ↔ Numbers Converter — Complete Guide (A → 1, B → 2 … Z → 26)
A → 1 B → 2 C → 3 D → 4 E → 5 F → 6 G → 7 H → 8 I → 9
J → 10 K → 11 L → 12 M → 13 N → 14 O → 15 P → 16 Q → 17 R → 18
S → 19 T → 20 U → 21 V → 22 W → 23 X → 24 Y → 25 Z → 26
Example: 8 5 12 → H E L → HEL
What is this?
This converter maps alphabetic characters to numeric codes (and back). The most common mapping is called the A1Z26 or alphabetical index:
- Letter → Number: A = 1, B = 2, …, Z = 26
- Number → Letter: 1 = A, 2 = B, …, 26 = Z
It’s a simple substitution system used in schooling, puzzles, simple ciphers, teaching, data-labeling, and lightweight obfuscation.
The basic formula
Use character code maths:
Letter → Number (for English A–Z):
n = ord(uppercase_letter) – ord(‘A’) + 1
- Example: ord(‘H’) = 72; 72 – 65 + 1 = 8.
Number → Letter (1–26):
letter = chr(number + ord(‘A’) – 1)
- Example: 8 + 65 – 1 = 72, chr(72) = ‘H’.
(If you prefer Excel: =CODE(UPPER(A1)) – 64 for letter→number, and =CHAR(number + 64) for number→letter.)
How the conversion works — step by step
Letters → Numbers
- Normalise text: Trim, convert to uppercase (unless preserving case), remove diacritics if needed.
- Tokenise: Separate letters; decide how to treat spaces or punctuation (skip or encode).
- Map each letter: Apply n = ord(letter) – 64 (for A=1).
- Output: Join numbers with chosen delimiter (space, comma, or padded).
Example: “HELLO” → tokens H E L L O → numbers 8 5 12 12 15.
Numbers → Letters
- Tokenise numbers: Use delimiter or fixed width (two digits).
- Validate: Ensure each token is in allowed range (1–26 for A1Z26).
- Map each number: letter = chr(n + 64).
- Reconstruct: Insert spaces or punctuation as requested.
Example: “8 5 12” → H E L → HEL.
Examples
- HEL → 8 5 12
- HELLO WORLD → 8 5 12 12 15 / 23 15 18 12 4 (use / or | for space)
- 08 05 12 12 15 → HELLO (fixed two-digit tokens)
- 1 2 3 → ABC
- Excel-style: 27 → AA, 52 → AZ, 53 → BA (use base-26 column logic)
FAQs
A: No. A1Z26 maps A→1. ASCII maps A→65. They serve different purposes.
A: Map each number (8→H, 5→E, 12→L). Result: HEL.
A: You shouldn’t — it’s ambiguous. Use clear delimiters or fixed-width tokens (e.g., two digits).
A: Not in A1Z26. Use Excel-style mapping (27→AA) or define 27 as a special token (space).
A: No. Convert to upper (or lower) first. Mapping is case-insensitive by design.
A: Normalize them first (é → E) or provide an extended alphabet mapping.
A: Yes — if the input is unambiguous (proper delimiters or fixed width) and the same mapping is used both ways.
A: No — A1Z26 is trivial and not secure cryptographically. It’s fine for teaching or puzzles only.
A: Common choices: /, 0, or 27 (but document your choice). The tool should let users choose.
A: Yes — that’s a different conversion (base-26 column logic). Offer it as an option.
