Dec	Hex	Oct	Binary	Char	Description

About ASCII Character Map & Binary Encoding Reference

ASCII (American Standard Code for Information Interchange) is a 7-bit character encoding standard published in 1963. It defines numerical representations for 128 specified characters, comprising numbers 0–9, English letters A–Z and a–z, punctuation symbols, and non-printable control characters.

Structure of the ASCII Table

Control Characters (0–31 & 127): Non-printable codes originally designed for teletype communication (e.g. NUL (0), BEL (7), BS (8), TAB (9), LF (10), CR (13), ESC (27), DEL (127)).
Printable Characters (32–126): The space character (32), followed by punctuation, numbers (48–57), uppercase letters (65–90), and lowercase letters (97–122).
Extended ASCII (128–255): 8-bit implementations (such as ISO 8859-1 and Windows-1252) that add accented letters, currency symbols, and box-drawing glyphs.

Quick Conversion Reference

This table displays exact character mappings across four primary numeral systems: Decimal (Base 10), Hexadecimal (Base 16), Octal (Base 8), and Binary (Base 2).

Frequently Asked Questions (FAQ)

How does ASCII relate to UTF-8?

UTF-8 was deliberately designed to be 100% backward-compatible with 7-bit ASCII. The first 128 characters of Unicode and UTF-8 match ASCII code points byte-for-byte.

What is the mathematical trick for ASCII uppercase / lowercase conversion?

In ASCII, toggling the 6th bit (value 32 or 0x20) switches an alphabetic character between uppercase and lowercase (e.g. 'A' (65) + 32 = 'a' (97)).