ASCII Table
Complete ASCII reference 0–127 with decimal, hex, binary and HTML entity values. Filter by character type, search by name or value, and convert text to ASCII codes in one step.
Last updated: May 2026
ASCII Reference Table
| Dec | Hex | Binary | HTML | Char | Description |
|---|
Showing 128 of 128 characters
Text ↔ ASCII Converter
Values separated by spaces. Non-ASCII characters (code > 127) are flagged.
What is ASCII?
ASCII stands for American Standard Code for Information Interchange. Defined in 1963 and standardised as ANSI X3.4 in 1968, it maps 128 characters to integer values 0–127. Each character fits in 7 bits, though computers typically store it in one 8-bit byte with the high bit unused.
The 128 code points split into two groups: control characters (0–31 and 127), which were designed to control teletype machines and data streams; and printable characters (32–126), which include the space, punctuation, digits, and the 52 Latin letters.
ASCII vs Unicode
Unicode was created to cover every writing system on Earth. The first 128 Unicode code points are identical to ASCII — so plain ASCII text is valid UTF-8 without any conversion. The difference shows up from code point 128 upward: ASCII stops there, while Unicode continues to over 1.1 million code points. For Western English text, ASCII and UTF-8 produce the same bytes.
Control vs Printable Characters
Control characters (0–31, 127) have no visual glyph. They were originally sent to hardware to perform actions: 7 (BEL) triggered an audible bell, 8 (BS) moved the print head back one space, 10 (LF) advanced the paper by one line. Today most are obsolete, but a handful remain vital:
| Dec | Hex | Abbr | Name | Modern use |
|---|---|---|---|---|
| 9 | 09 | HT | Horizontal Tab | Indentation in code and TSV files |
| 10 | 0A | LF | Line Feed | Newline on Unix/Linux/macOS |
| 13 | 0D | CR | Carriage Return | Part of CRLF newline on Windows |
| 27 | 1B | ESC | Escape | ANSI terminal escape sequences |
| 32 | 20 | SP | Space | Word separation (first printable char) |
| 127 | 7F | DEL | Delete | Erase; still used in some terminal protocols |
Practical uses for developers
- HTML escaping: Characters like
&,<,>, and"must be escaped as HTML entities to render correctly in markup. - Serial / UART debugging: Microcontroller output is often raw bytes. Knowing the ASCII range helps you tell text from binary garbage at a glance.
- Data cleaning: CSV and TSV parsers break on stray control characters. Scanning for bytes below 32 (except 9, 10, 13) catches invisible corruption.
- URL encoding: Characters outside the printable ASCII "safe" set must be percent-encoded in URLs.
- Retro/embedded systems: Many microcontrollers (Arduino, PIC, AVR) communicate via ASCII-encoded command strings over serial.
- Sorting: ASCII defines lexicographic order. Digits (48–57) sort before uppercase (65–90) which sort before lowercase (97–122) — important for case-sensitive sort comparisons.
Frequently Asked Questions
Why does ASCII only go to 127?
The original ASCII standard used 7 bits, which gives exactly 128 values (0–127). In the 1960s, storage was expensive and 7 bits was judged sufficient for English text plus control codes. The 8th bit was left free for parity checking. Later, "extended ASCII" code pages (128–255) filled that 8th bit differently depending on the vendor — which is exactly the kind of fragmentation that Unicode later solved.
What is the difference between LF and CRLF?
LF (decimal 10, hex 0A) is a single Line Feed character used as the line ending on Unix, Linux and macOS. CRLF is the two-byte sequence Carriage Return + Line Feed (decimal 13 then 10) used on Windows and in many internet protocols (HTTP headers, SMTP). When you open a Windows text file on a Unix system without conversion, you may see stray ^M characters — those are the CR bytes.
How do I use HTML entities for special characters?
The five characters that must be escaped in HTML are: & → &, < → <, > → >, " → ", and ' → ' (or ' in HTML5). Any character can also be referenced by its decimal code point: A renders the letter A. The converter above outputs the minimal entity form for each character.
Why are lowercase letters 32 higher than uppercase in ASCII?
By design. The difference between the ASCII code for 'A' (65) and 'a' (97) is exactly 32 — which is the value of bit 5 (the 0x20 bit). This means you can toggle case by flipping a single bit, or by adding/subtracting 32. It also means a bitwise OR with 0x20 lowercases a letter, and an AND with 0xDF uppercases it — a trick still used in performance-sensitive code.
What happens to ASCII codes above 127?
Codes 128–255 are outside standard ASCII. In the 8-bit era, different vendors defined them differently: Windows uses Windows-1252, Latin countries used ISO-8859-1, and IBM PCs used Code Page 437. These incompatible encodings caused the "mojibake" (garbled text) problem. Modern systems default to UTF-8, where bytes above 127 are part of multi-byte sequences representing Unicode characters — none of them conflict with the 0–127 ASCII range.