What is the standard ASCII character set?

The standard American Standard Code for Information Interchange (ASCII) defines 128 character codes (0 through 127, or 0x00 to 0x7F). It comprises 33 non-printable control characters and 95 printable characters including letters, digits, and punctuation.

What are ASCII control characters (0x00 to 0x1F)?

Control characters were originally created to control teletypewriters and serial communication hardware. Examples include NUL (0x00, Null), LF (0x0A, Line Feed), CR (0x0D, Carriage Return), and ESC (0x1B, Escape).

Why do uppercase and lowercase ASCII letters differ by exactly 0x20 (32)?

ASCII was engineered so that lowercase letters are located exactly 32 positions after their uppercase counterparts (e.g., 'A' = 0x41 = 65, 'a' = 0x61 = 97). In binary, this corresponds to flipping a single bit (bit 5, weight 32), making case conversions instantaneous.

What is the difference between standard ASCII and extended ASCII?

Standard ASCII uses 7 bits (0–127). Extended ASCII refers to various 8-bit character sets (like ISO-8859-1 or Windows-1252) that utilize codes 128–255 (0x80 to 0xFF) for accented letters, currency symbols, and graphical box characters.

How do ASCII numbers (0–9) map to hexadecimal?

ASCII digits '0' through '9' map to decimal 48 through 57, which in hexadecimal is 0x30 through 0x39. Subtracting 0x30 from an ASCII digit character immediately yields its numerical value.

Can I search by decimal, hex, or character symbol in this table?

Yes. The interactive search filter responds instantaneously to character literals, hex codes (with or without 0x), decimal numbers, or control character abbreviations.

Standard ASCII Table & Character Reference

Complete 0 to 127 ASCII character chart displaying decimal codes, hexadecimal values, 8-bit binary patterns, octal values, control character descriptions, and printable characters.

Showing 128 of 128 standard ASCII characters

Dec	Hex	Octal	Binary	Symbol	Description
0	0x00	000	00000000	NUL	Null Character
1	0x01	001	00000001	SOH	Start of Header
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
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	!	Printable character '!'
34	0x22	042	00100010	"	Printable character '"'
35	0x23	043	00100011	#	Printable character '#'
36	0x24	044	00100100	$	Printable character '$'
37	0x25	045	00100101	%	Printable character '%'
38	0x26	046	00100110	&	Printable character '&'
39	0x27	047	00100111	'	Printable character '''
40	0x28	050	00101000	(	Printable character '('
41	0x29	051	00101001	)	Printable character ')'
42	0x2A	052	00101010	*	Printable character '*'
43	0x2B	053	00101011	+	Printable character '+'
44	0x2C	054	00101100	,	Printable character ','
45	0x2D	055	00101101	-	Printable character '-'
46	0x2E	056	00101110	.	Printable character '.'
47	0x2F	057	00101111	/	Printable character '/'
48	0x30	060	00110000	0	Printable character '0'
49	0x31	061	00110001	1	Printable character '1'
50	0x32	062	00110010	2	Printable character '2'
51	0x33	063	00110011	3	Printable character '3'
52	0x34	064	00110100	4	Printable character '4'
53	0x35	065	00110101	5	Printable character '5'
54	0x36	066	00110110	6	Printable character '6'
55	0x37	067	00110111	7	Printable character '7'
56	0x38	070	00111000	8	Printable character '8'
57	0x39	071	00111001	9	Printable character '9'
58	0x3A	072	00111010	:	Printable character ':'
59	0x3B	073	00111011	;	Printable character ';'
60	0x3C	074	00111100	<	Printable character '<'
61	0x3D	075	00111101	=	Printable character '='
62	0x3E	076	00111110	>	Printable character '>'
63	0x3F	077	00111111	?	Printable character '?'
64	0x40	100	01000000	@	Printable character '@'
65	0x41	101	01000001	A	Printable character 'A'
66	0x42	102	01000010	B	Printable character 'B'
67	0x43	103	01000011	C	Printable character 'C'
68	0x44	104	01000100	D	Printable character 'D'
69	0x45	105	01000101	E	Printable character 'E'
70	0x46	106	01000110	F	Printable character 'F'
71	0x47	107	01000111	G	Printable character 'G'
72	0x48	110	01001000	H	Printable character 'H'
73	0x49	111	01001001	I	Printable character 'I'
74	0x4A	112	01001010	J	Printable character 'J'
75	0x4B	113	01001011	K	Printable character 'K'
76	0x4C	114	01001100	L	Printable character 'L'
77	0x4D	115	01001101	M	Printable character 'M'
78	0x4E	116	01001110	N	Printable character 'N'
79	0x4F	117	01001111	O	Printable character 'O'
80	0x50	120	01010000	P	Printable character 'P'
81	0x51	121	01010001	Q	Printable character 'Q'
82	0x52	122	01010010	R	Printable character 'R'
83	0x53	123	01010011	S	Printable character 'S'
84	0x54	124	01010100	T	Printable character 'T'
85	0x55	125	01010101	U	Printable character 'U'
86	0x56	126	01010110	V	Printable character 'V'
87	0x57	127	01010111	W	Printable character 'W'
88	0x58	130	01011000	X	Printable character 'X'
89	0x59	131	01011001	Y	Printable character 'Y'
90	0x5A	132	01011010	Z	Printable character 'Z'
91	0x5B	133	01011011	[	Printable character '['
92	0x5C	134	01011100	\	Printable character '\'
93	0x5D	135	01011101	]	Printable character ']'
94	0x5E	136	01011110	^	Printable character '^'
95	0x5F	137	01011111	_	Printable character '_'
96	0x60	140	01100000	`	Printable character '`'
97	0x61	141	01100001	a	Printable character 'a'
98	0x62	142	01100010	b	Printable character 'b'
99	0x63	143	01100011	c	Printable character 'c'
100	0x64	144	01100100	d	Printable character 'd'
101	0x65	145	01100101	e	Printable character 'e'
102	0x66	146	01100110	f	Printable character 'f'
103	0x67	147	01100111	g	Printable character 'g'
104	0x68	150	01101000	h	Printable character 'h'
105	0x69	151	01101001	i	Printable character 'i'
106	0x6A	152	01101010	j	Printable character 'j'
107	0x6B	153	01101011	k	Printable character 'k'
108	0x6C	154	01101100	l	Printable character 'l'
109	0x6D	155	01101101	m	Printable character 'm'
110	0x6E	156	01101110	n	Printable character 'n'
111	0x6F	157	01101111	o	Printable character 'o'
112	0x70	160	01110000	p	Printable character 'p'
113	0x71	161	01110001	q	Printable character 'q'
114	0x72	162	01110010	r	Printable character 'r'
115	0x73	163	01110011	s	Printable character 's'
116	0x74	164	01110100	t	Printable character 't'
117	0x75	165	01110101	u	Printable character 'u'
118	0x76	166	01110110	v	Printable character 'v'
119	0x77	167	01110111	w	Printable character 'w'
120	0x78	170	01111000	x	Printable character 'x'
121	0x79	171	01111001	y	Printable character 'y'
122	0x7A	172	01111010	z	Printable character 'z'
123	0x7B	173	01111011	{	Printable character '{'
124	0x7C	174	01111100	\|	Printable character '\|'
125	0x7D	175	01111101	}	Printable character '}'
126	0x7E	176	01111110	~	Printable character '~'
127	0x7F	177	01111111	DEL	Delete

Structure of the 7-Bit ASCII Character Set

The ASCII specification partitions the 128 available 7-bit values into distinct operational functional ranges:

0 to 31 (0x00 to 0x1F): Control Codes: Device signals like Line Feed (0x0A), Carriage Return (0x0D), and Tab (0x09).
32 to 64 (0x20 to 0x40): Space, Punctuation & Digits: Space (0x20), numbers '0'–'9' (0x30 to 0x39), and symbols.
65 to 90 (0x41 to 0x5A): Uppercase Letters: 'A' through 'Z'. Notice that adding 0x20 (32) converts any uppercase letter to lowercase!
97 to 122 (0x61 to 0x7A): Lowercase Letters: 'a' through 'z'.
127 (0x7F): DEL (Delete): Originally used on punched tape to punch out all 7 holes, effectively erasing an unwanted character.

To convert arbitrary text strings into hex bytes, use our Text to Hex Converter.

Frequently Asked Questions

Direct answers to technical and practical questions regarding this tool and base-16 conversion.

What is ASCII?

ASCII stands for American Standard Code for Information Interchange. Established in 1963 by the American National Standards Institute (ANSI), it assigns standard 7-bit numerical values (0 to 127) to English letters, numbers, punctuation marks, and hardware control characters.

What are the ASCII control characters (0–31)?

The first 32 codes (0 to 31) are non-printable device control characters originally designed for teletypes and early computer peripherals. They include commands like NUL (null), LF (line feed / newline, 0x0A), CR (carriage return, 0x0D), BS (backspace, 0x08), and BEL (bell sound, 0x07).

What is the ASCII value of space in hex?

The space character is decimal 32, which is 0x20 in hexadecimal (00100000 in binary). It is the very first printable character in the ASCII specification.

What is the relationship between ASCII and Unicode / UTF-8?

Standard 7-bit ASCII is identical to the first 128 code points of Unicode (U+0000 to U+007F). In UTF-8, these characters are encoded as a single byte with the most significant bit set to 0. This guarantees 100% backward compatibility with vintage ASCII software and files.

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Reference

Hexadecimal Conversion Chart (0–255)

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Sources & Technical References

[1]
ANSI INCITS 4-1986 (R2012): 7-Bit ASCII Standard — American National Standards Institute (ANSI)
Official specification defining 7-bit ASCII character codes and control functions.

Technical Verification & Editorial Accountability

Written by Sarah Chen (Embedded Systems Engineer) • Verified by Marcus Brody, PE

Reviewed: 2026-10-02MethodologyEditorial PolicyReport Error