What is ASCII and why does it matter in programming?

ASCII is the American Standard Code for Information Interchange, a character encoding standard that maps 128 characters to numeric values 0-127. It matters because virtually every modern encoding (UTF-8, ISO-8859, etc.) is backward compatible with ASCII. Understanding ASCII values is essential for string manipulation, data parsing, network protocols, file formats, and debugging encoding issues in any programming language.

What are ASCII control characters?

Control characters (decimal 0-31 and 127) are non-printable codes originally designed to control hardware devices like printers and terminals. Common ones include NUL (0, null terminator in C strings), HT (9, horizontal tab), LF (10, line feed/newline on Unix), CR (13, carriage return), and ESC (27, escape sequences). Many remain critical in modern computing — for example, LF and CR define line endings in text files.

What is the difference between ASCII and Unicode?

ASCII defines 128 characters using 7 bits and only covers basic English letters, digits, and symbols. Unicode is a superset that supports over 149,000 characters across all writing systems, emojis, and symbols. UTF-8, the most common Unicode encoding, uses the same byte values as ASCII for characters 0-127, making it fully backward compatible. ASCII is a subset of UTF-8.

How do I convert between ASCII decimal and hexadecimal values?

Each ASCII character has equivalent decimal and hex values. For example, uppercase A is decimal 65 (hex 41), digit 0 is decimal 48 (hex 30), and space is decimal 32 (hex 20). This table shows all conversions. In code, you can use functions like Python chr(65) or JavaScript String.fromCharCode(65) to convert numeric values to characters.

Why does the table show 128 characters instead of 256?

Standard ASCII uses 7 bits, giving exactly 128 characters (0-127). Values 128-255 are part of "Extended ASCII" which varies by encoding (like ISO-8859-1 or Windows-1252). This table shows the universally standard 128-character set that is identical across all platforms and encodings. Extended character sets are not part of the official ASCII specification.

What are the most commonly used ASCII values for programming?

Key values include: 0 (NUL, C string terminator), 9 (Tab), 10 (LF/newline), 13 (CR/carriage return), 32 (Space), 48-57 (digits 0-9), 65-90 (uppercase A-Z), 97-122 (lowercase a-z). The difference between uppercase and lowercase letters is always 32 — adding 32 to an uppercase ASCII value gives its lowercase equivalent.

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ASCII table

Complete ASCII character reference with all 128 characters. Search by decimal, hex, binary, or description. Click any row to copy.

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128 characters shown

Dec	Hex	Oct	Binary	Char	Description
0	0x00	000	00000000	NUL	Null character
1	0x01	001	00000001	SOH	Start of Heading
2	0x02	002	00000010	STX	Start of Text
3	0x03	003	00000011	ETX	End of Text
4	0x04	004	00000100	EOT	End of Transmission
5	0x05	005	00000101	ENQ	Enquiry
6	0x06	006	00000110	ACK	Acknowledge
7	0x07	007	00000111	BEL	Bell (alert)
8	0x08	010	00001000	BS	Backspace
9	0x09	011	00001001	HT	Horizontal Tab
10	0x0A	012	00001010	LF	Line Feed (newline)
11	0x0B	013	00001011	VT	Vertical Tab
12	0x0C	014	00001100	FF	Form Feed (new page)
13	0x0D	015	00001101	CR	Carriage Return
14	0x0E	016	00001110	SO	Shift Out
15	0x0F	017	00001111	SI	Shift In
16	0x10	020	00010000	DLE	Data Link Escape
17	0x11	021	00010001	DC1	Device Control 1 (XON)
18	0x12	022	00010010	DC2	Device Control 2
19	0x13	023	00010011	DC3	Device Control 3 (XOFF)
20	0x14	024	00010100	DC4	Device Control 4
21	0x15	025	00010101	NAK	Negative Acknowledge
22	0x16	026	00010110	SYN	Synchronous Idle
23	0x17	027	00010111	ETB	End of Transmission Block
24	0x18	030	00011000	CAN	Cancel
25	0x19	031	00011001	EM	End of Medium
26	0x1A	032	00011010	SUB	Substitute
27	0x1B	033	00011011	ESC	Escape
28	0x1C	034	00011100	FS	File Separator
29	0x1D	035	00011101	GS	Group Separator
30	0x1E	036	00011110	RS	Record Separator
31	0x1F	037	00011111	US	Unit Separator
32	0x20	040	00100000	Space	Space
33	0x21	041	00100001	!	Exclamation mark
34	0x22	042	00100010	"	Double quote
35	0x23	043	00100011	#	Hash / Number sign
36	0x24	044	00100100	$	Dollar sign
37	0x25	045	00100101	%	Percent sign
38	0x26	046	00100110	&	Ampersand
39	0x27	047	00100111	'	Single quote (apostrophe)
40	0x28	050	00101000	(	Left parenthesis
41	0x29	051	00101001	)	Right parenthesis
42	0x2A	052	00101010	*	Asterisk
43	0x2B	053	00101011	+	Plus sign
44	0x2C	054	00101100	,	Comma
45	0x2D	055	00101101	-	Hyphen-minus
46	0x2E	056	00101110	.	Period (full stop)
47	0x2F	057	00101111	/	Slash (solidus)
48	0x30	060	00110000	0	Digit zero
49	0x31	061	00110001	1	Digit one
50	0x32	062	00110010	2	Digit two
51	0x33	063	00110011	3	Digit three
52	0x34	064	00110100	4	Digit four
53	0x35	065	00110101	5	Digit five
54	0x36	066	00110110	6	Digit six
55	0x37	067	00110111	7	Digit seven
56	0x38	070	00111000	8	Digit eight
57	0x39	071	00111001	9	Digit nine
58	0x3A	072	00111010	:	Colon
59	0x3B	073	00111011	;	Semicolon
60	0x3C	074	00111100	<	Less-than sign
61	0x3D	075	00111101	=	Equals sign
62	0x3E	076	00111110	>	Greater-than sign
63	0x3F	077	00111111	?	Question mark
64	0x40	100	01000000	@	At sign
65	0x41	101	01000001	A	Uppercase letter A
66	0x42	102	01000010	B	Uppercase letter B
67	0x43	103	01000011	C	Uppercase letter C
68	0x44	104	01000100	D	Uppercase letter D
69	0x45	105	01000101	E	Uppercase letter E
70	0x46	106	01000110	F	Uppercase letter F
71	0x47	107	01000111	G	Uppercase letter G
72	0x48	110	01001000	H	Uppercase letter H
73	0x49	111	01001001	I	Uppercase letter I
74	0x4A	112	01001010	J	Uppercase letter J
75	0x4B	113	01001011	K	Uppercase letter K
76	0x4C	114	01001100	L	Uppercase letter L
77	0x4D	115	01001101	M	Uppercase letter M
78	0x4E	116	01001110	N	Uppercase letter N
79	0x4F	117	01001111	O	Uppercase letter O
80	0x50	120	01010000	P	Uppercase letter P
81	0x51	121	01010001	Q	Uppercase letter Q
82	0x52	122	01010010	R	Uppercase letter R
83	0x53	123	01010011	S	Uppercase letter S
84	0x54	124	01010100	T	Uppercase letter T
85	0x55	125	01010101	U	Uppercase letter U
86	0x56	126	01010110	V	Uppercase letter V
87	0x57	127	01010111	W	Uppercase letter W
88	0x58	130	01011000	X	Uppercase letter X
89	0x59	131	01011001	Y	Uppercase letter Y
90	0x5A	132	01011010	Z	Uppercase letter Z
91	0x5B	133	01011011	[	Left square bracket
92	0x5C	134	01011100	\	Backslash
93	0x5D	135	01011101	]	Right square bracket
94	0x5E	136	01011110	^	Caret (circumflex)
95	0x5F	137	01011111	_	Underscore
96	0x60	140	01100000	`	Grave accent (backtick)
97	0x61	141	01100001	a	Lowercase letter a
98	0x62	142	01100010	b	Lowercase letter b
99	0x63	143	01100011	c	Lowercase letter c
100	0x64	144	01100100	d	Lowercase letter d
101	0x65	145	01100101	e	Lowercase letter e
102	0x66	146	01100110	f	Lowercase letter f
103	0x67	147	01100111	g	Lowercase letter g
104	0x68	150	01101000	h	Lowercase letter h
105	0x69	151	01101001	i	Lowercase letter i
106	0x6A	152	01101010	j	Lowercase letter j
107	0x6B	153	01101011	k	Lowercase letter k
108	0x6C	154	01101100	l	Lowercase letter l
109	0x6D	155	01101101	m	Lowercase letter m
110	0x6E	156	01101110	n	Lowercase letter n
111	0x6F	157	01101111	o	Lowercase letter o
112	0x70	160	01110000	p	Lowercase letter p
113	0x71	161	01110001	q	Lowercase letter q
114	0x72	162	01110010	r	Lowercase letter r
115	0x73	163	01110011	s	Lowercase letter s
116	0x74	164	01110100	t	Lowercase letter t
117	0x75	165	01110101	u	Lowercase letter u
118	0x76	166	01110110	v	Lowercase letter v
119	0x77	167	01110111	w	Lowercase letter w
120	0x78	170	01111000	x	Lowercase letter x
121	0x79	171	01111001	y	Lowercase letter y
122	0x7A	172	01111010	z	Lowercase letter z
123	0x7B	173	01111011	{	Left curly brace
124	0x7C	174	01111100	\|	Vertical bar (pipe)
125	0x7D	175	01111101	}	Right curly brace
126	0x7E	176	01111110	~	Tilde
127	0x7F	177	01111111	DEL	Delete

What this tool does

Full 128-character ASCII table with all encodings
Decimal, hex, octal, and binary representations
Control character names and descriptions
Search and filter by any column value
Click to copy any character instantly
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The short version

What is ASCII Table?

ASCII (American Standard Code for Information Interchange) is the foundational character encoding standard used in computers and digital devices.

It assigns a unique numeric value (0-127) to 128 characters including uppercase and lowercase English letters, digits 0-9, punctuation marks, special symbols, and 33 control characters used for device communication. This ASCII table tool gives you a complete, searchable reference for all 128 ASCII characters with their decimal, hexadecimal, octal, and binary representations. Control characters (0-31 and 127) are non-printable codes originally designed for hardware like printers and terminals — they include NUL (null), LF (line feed/newline), CR (carriage return), ESC (escape), TAB, and others that remain critical in modern programming. Printable characters (32-126) include everything you type on a keyboard. You can search by any value, filter between control and printable characters, and click any row to copy the character. All processing runs entirely in your browser.

Step by step

How to use ASCII Table

1
Browse or search the table
Scroll through all 128 ASCII characters or use the search box to find a character by its decimal value, hexadecimal code, character symbol, or description. The search matches across all columns instantly.
2
Filter by character type
Use the filter tabs to narrow the view. "Control" shows only non-printable control characters (0-31 and DEL). "Printable" shows visible characters (32-126). "Extended Info" adds a range reference guide showing which ASCII ranges correspond to which character groups.
3
Copy characters
Click any row in the table to copy the character to your clipboard. For printable characters, the actual character is copied. For control characters, the abbreviation and numeric values are copied so you have a useful reference.

What's inside

Everything this tool
does for you

Complete 128-character ASCII table with all standard characters
Four numeric representations: decimal, hexadecimal, octal, and binary
Named control characters with full descriptions (NUL, SOH, STX, etc.)
Instant search across decimal, hex, character, and description fields
Filter tabs for All, Control, Printable, and Extended Info views
One-click copy for any character or control code reference
Responsive table with horizontal scroll for mobile devices
Zero server calls — runs entirely in your browser

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What is ASCII Table?

How to use ASCII Table

Browse or search the table

Filter by character type

Copy characters

Everything this tooldoes for you

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Frequently asked questions

What is ASCII and why does it matter in programming?

What are ASCII control characters?

What is the difference between ASCII and Unicode?

How do I convert between ASCII decimal and hexadecimal values?

Why does the table show 128 characters instead of 256?

What are the most commonly used ASCII values for programming?

This tool fixed one thing.Now fix the whole site.

Everything this tool
does for you

This tool fixed one thing.
Now fix the whole site.