ASCII 27
Escape (ESC)
Control character
The Escape key. Introduces ANSI escape sequences (e.g. \x1B[31m for red text).
Common uses & context
Decimal 27 (0x1B) is the Escape control character — one of the 33 non-printing codes in the C0 control block (0–31 plus DEL at 127). Control characters were designed to command teletype and terminal hardware rather than to represent visible glyphs, so ESC produces no letter, digit, or symbol on screen. Its8-bit binary form is 00011011 and its octal value is 0033.
The Escape key. Introduces ANSI escape sequences (e.g. \x1B[31m for red text).
BecauseESC is invisible, it is easiest to work with by its numeric code. In most languages you can produce it with the escape or code-point form shown below, and detect it by comparing a byte against 27 (0x1B). When it turns up unexpectedly in text — pasted from a terminal, a legacy file, or a binary blob — it is usually the cause of "invisible character" bugs that break parsing or comparisons.
All encodings at a glance
| Decimal | 27 |
| Hexadecimal | 0x1B |
| Octal | 0033 |
| Binary | 00011011 |
| HTML numeric entity |  |
| URL encoding | %1B |
| UTF-8 bytes | 0x1B |
Code snippets
JavaScript
String.fromCharCode(27); // "ESC"
27.toString(16); // "1b"Python
chr(27) # control char ESC
ord(chr(27)) # 27
hex(27) # '0x1b'HTML
 <!-- numeric entity (no named entity for this character) -->Programming notes
- ▸Detect it by numeric comparison: byte === 27 (0x1B). It has no printable glyph to match on.
- ▸Control characters below 32 are stripped or rejected by many text validators — check for them when sanitizing user input.
- ▸In a hex dump ESC shows as 1B; in a "cat -v" style view it may appear as a caret sequence.
Frequently asked questions
What character is ASCII code 27?
ASCII code 27 is Escape (ESC), a non-printing control/whitespace character. In hexadecimal it is 0x1B and in binary 00011011. It has no visible glyph — it controls formatting or hardware instead of drawing a symbol.
What is 0x1B in ASCII?
Hexadecimal 0x1B equals decimal 27, which is theEscape control character (ESC). To convert hex to ASCII yourself, read the two hex digits as a base-16 number (0x1B = 27) and look up that code point.
How do I write the character with code 27 in code?
In JavaScript use String.fromCharCode(27); in Python use chr(27); in HTML use the numeric entity . In a URL it is percent-encoded as %1B, and in UTF-8 it is stored as the byte sequence 0x1B.
Is ASCII 27 (ESC) printable?
No. ESC (code 27) is a control character with no visible glyph. It instructs software or hardware rather than displaying a symbol, which is why it often appears as an invisible or replacement character when it leaks into ordinary text.