ASCII – the American Standard Code for Information Interchange, first published in 1963 – gives a number from 0 to 127 to every English letter, digit, punctuation mark and a set of control codes. Codes 0–31 and 127 are invisible control characters (tab, line feed, escape…), 32 is the space, 48–57 are the digits, 65–90 the capital letters and 97–122 the lowercase letters. Unicode keeps exactly these numbers for its first 128 characters, so ASCII is still the foundation of every modern text encoding.
Because the codes are numbers, they can be written in any base: “a” is 97 in decimal, 61 in hex, 01100001 in binary and 141 in octal. This converter accepts any of those forms as input and gives you all the others, so you can decode a list of numbers from a puzzle, check the code of a character in a program or produce a binary greeting.
Codes 128–255 are not ASCII but “extended ASCII”. On Western Windows systems they follow Windows-1252, where 128 is € and 233 is é; the converter uses that table and shows the Unicode code point for anything beyond it.
How to use the ASCII Converter
- I am entering
- Input
- Separator between bytes
- Custom separator
Everything is calculated in your browser, so results appear instantly and nothing you type is sent to a server.
How it works
Choose what you are entering. Text is split into characters and each is looked up in the ASCII/Windows-1252 table; numbers are read in the chosen base, one value per group (long binary strings are cut into 8-bit pieces and long hex strings into pairs), and converted into characters.
Worked example
Convert the word ASCII. A = 65, S = 83, C = 67, I = 73, I = 73. In hex that is 41 53 43 49 49, in binary 01000001 01010011 01000011 01001001 01001001 and in octal 101 123 103 111 111. Entering “65 83 67 73 73” with “Decimal codes” selected gives back the word.
ASCII ranges at a glance
| Decimal | Hex | Characters |
|---|---|---|
| 0–31 | 00–1F | Control codes (tab 9, line feed 10, carriage return 13, escape 27) |
| 32 | 20 | Space |
| 33–47 | 21–2F | ! ” # $ % & ‘ ( ) * + , – . / |
| 48–57 | 30–39 | Digits 0–9 |
| 58–64 | 3A–40 | : ; < = > ? @ |
| 65–90 | 41–5A | A–Z |
| 91–96 | 5B–60 | [ ] ^ _ ` |
| 97–122 | 61–7A | a–z |
| 123–126 | 7B–7E | { | } ~ |
| 127 | 7F | DEL (control) |
Formula
ASCII code = position of the character in the ASCII table (0–127)
hex = code in base 16 · binary = code in base 2 (8 digits) · octal = code in base 8
Worked example
Inputs — I am entering: Text (visible characters); Input: ASCII; Separator between bytes: Space.
Results — ASCII codes (decimal) = 65 83 67 73 73; Visible text = ASCII; Binary = 01000001 01010011 01000011 01001001 01001001; Hexadecimal = 41 53 43 49 49; Octal = 101 123 103 111 111; Number of characters = 5.
Key terms
- ASCII
- A 7-bit character code with 128 values, standardised as ANSI X3.4.
- Control character
- A non-printing code (0–31, 127) used to control devices, such as line feed (10) or escape (27).
- Extended ASCII
- 8-bit code pages that use 128–255 for extra characters; Windows-1252 is the most common.
- Code page
- A table that assigns characters to byte values.
Frequently asked questions
What is the ASCII code of “A”?
65 in decimal, 41 in hex, 01000001 in binary and 101 in octal.
What is the ASCII value of “a”?
97 (hex 61, binary 01100001, octal 141). Lowercase letters are always 32 higher than their capitals.
How many characters does ASCII have?
128: 33 control codes (0–31 and 127) and 95 printable characters including the space.
Is extended ASCII the same everywhere?
No. Codes 128–255 depend on the code page; Windows-1252 (used here) and ISO 8859-1 agree except for 128–159, where Windows-1252 has €, “ ” and other symbols.
What is the ASCII code for a space?
32 (hex 20).
How are digits stored?
As codes 48–57, so the character “7” is 55, not 7. Subtract 48 to get the digit’s value.
What is the difference between ASCII and Unicode?
Unicode is a superset: its first 128 code points are ASCII, followed by more than 150,000 other characters.