ASCII Table — Complete Character Code Reference

Introduction

ASCII (American Standard Code for Information Interchange) is the foundational character encoding system used in computers. It assigns a unique numeric code to 128 characters including letters, digits, punctuation marks, and control characters. Every programmer, computer science student, and IT professional encounters ASCII when working with text data, serial communication, or debugging binary content.

This reference guide covers the full ASCII table, explains the encoding structure, and shows practical use cases.

What is ASCII?

ASCII uses 7 bits to represent 128 characters (codes 0–127). Each character maps to a fixed integer value. For example, uppercase ‘A’ is always 65, lowercase ‘a’ is always 97, and the digit ‘0’ is always 48 — regardless of which programming language or operating system you use.

ASCII Structure

Range	Category	Description
0–31	Control characters	Non-printable (newline, tab, escape, etc.)
32	Space	Blank space character
33–47	Punctuation	! ” # $ % & ’ ( ) * + , - . /
48–57	Digits	0 through 9
58–64	Punctuation	: ; < = > ? @
65–90	Uppercase letters	A through Z
91–96	Punctuation	[ \ ] ^ _ `
97–122	Lowercase letters	a through z
123–126	Punctuation	{ | } ~
127	Control	DEL (delete)

Key ASCII Values to Remember

Character	Decimal	Hex	Binary
Space	32	20	0100000
0 (digit)	48	30	0110000
9 (digit)	57	39	0111001
A	65	41	1000001
Z	90	5A	1011010
a	97	61	1100001
z	122	7A	1111010
Newline (LF)	10	0A	0001010
Tab	9	09	0001001

Useful Patterns

Uppercase ↔ Lowercase

The difference between uppercase and lowercase letters is exactly 32 (one bit flip at position 5).

• ‘A’ = 65, ‘a’ = 97 → difference = 32
• To convert uppercase to lowercase: add 32
• To convert lowercase to uppercase: subtract 32

Digit Character to Number

Character ‘0’ is code 48. To get the numeric value of any digit character, subtract 48.

• ‘7’ = 55 → 55 − 48 = 7

Checking Character Type

• Digit: code 48–57
• Uppercase: code 65–90
• Lowercase: code 97–122

Control Characters (0–31)

Code	Abbreviation	Meaning
0	NUL	Null (string terminator in C)
7	BEL	Bell (audible alert)
8	BS	Backspace
9	HT	Horizontal tab
10	LF	Line feed (newline on Unix)
13	CR	Carriage return
27	ESC	Escape

Extended ASCII (128–255)

Standard ASCII covers 0–127. Extended ASCII (codes 128–255) varies by system and code page (like Windows-1252, ISO-8859-1). Modern systems prefer Unicode (UTF-8) which is backward-compatible with standard ASCII for codes 0–127.

Practical Applications

• Serial communication — UART protocols transmit ASCII bytes for text data
• Programming — String manipulation, character comparisons, encoding/decoding
• Debugging — Reading hex dumps of text files and network packets
• CTF challenges — Cryptography puzzles often involve ASCII encoding
• Embedded systems — LCD displays and keyboards use ASCII codes

Convert Online

Use the free ASCII Converter on Numverto to convert any text to ASCII codes (decimal, hex, binary, octal) or decode numbers back to characters. Also browse our complete ASCII Table page for a printable lookup reference.

Frequently Asked Questions

What is the ASCII code for ‘A’?

Uppercase ‘A’ has ASCII code 65 in decimal, 41 in hexadecimal, and 01000001 in binary.

How many characters does ASCII support?

Standard ASCII supports 128 characters (7-bit encoding, codes 0–127). Extended ASCII uses 8 bits for 256 characters, but the extended range varies by platform.

What is the difference between ASCII and Unicode?

ASCII encodes 128 characters using 7 bits. Unicode supports over 140,000 characters from all writing systems. UTF-8 (the most common Unicode encoding) is backward-compatible — the first 128 UTF-8 codes are identical to ASCII.

Why does ‘A’ have code 65 and not 1?

Codes 0–31 are reserved for control characters (like newline and tab), code 32 is space, and codes 33–64 are punctuation and digits. Uppercase letters begin at 65, with lowercase at 97 (offset by 32 for easy conversion).

How do I convert a string to ASCII codes manually?

Look up each character in the ASCII table and write its decimal (or hex) code. For “Hi”: H=72, i=105. Use the Numverto ASCII Converter to do this instantly for any string.