ASCII Code Table

ASCII (American Standard Code for Information Interchange) includes 128 characters (0-127). Codes 0-31 and 127 are control characters; 32-126 are printable characters.

How It Works

ASCII (American Standard Code for Information Interchange) encodes characters in 7 bits, giving code points 0–127, and became the de-facto standard for early computers. Code points 0–31 and 127 are control characters (e.g. LF, TAB, CR); 32–126 are printable (letters, digits, punctuation).

Because 7 bits only covers English, "extended ASCII" uses the 8th bit for 128–255, but that range has no single standard — Windows-1252, ISO-8859-1 and others disagree, which is why raw binary text often shows mojibake across systems.

When to Use This Table

This table is for mapping a character to its code point and byte. Debugging mojibake, validating an encoding conversion, or checking control-character numbers in a protocol all need it. But there is a prerequisite question: if your goal is human-readable text, the encoding scheme (UTF-8 / GBK / Shift-JIS) determines the outcome far more than the code point does; this ASCII table only matters once you are working at the byte level.

When not to consult it: you are handling Chinese, Japanese or emoji. This table covers the 7-bit 0-127 range; everything above 128 is extension territory interpreted differently by each encoding, so deriving non-ASCII bytes from this table is guaranteed to be wrong. Those questions belong to the Character Encodings page, not here.

Rule of thumb: consult this table when the number is 0-127 and you need to know what the byte means. Above 127, settle the encoding scheme first and only then talk code points. Conflating the two layers is the most common source of the mistake where a UTF-8 multi-byte sequence gets treated as several separate characters.

Another bad signal: you only want to know the length of a string. Character count, byte count and code point count are three different quantities. They coincide inside ASCII and diverge sharply outside it — a single emoji is typically one character, two code points and four UTF-8 bytes.

Boundaries and Common Pitfalls

Control character numbering varies by dialect
The 0-31 and 127 range is control territory, but the mapping from number to action differs by dialect. Traditional ASCII assigns 7 to bell, 8 to backspace, 9 to tab, 10 to line feed and 13 to carriage return, while Windows consoles make backspace 8 and a newline the two-byte sequence 13 followed by 10. When writing a protocol across systems, never assume that 10 means newline; state which convention you are speaking.
There is no such thing as "extended ASCII"
The 128-255 range is often called extended ASCII, but no single standard defines it. ISO-8859-1 (Latin-1) and Windows-1252 differ only across 0x80-0x9F, which is exactly the boundary between control and printable characters, so mixing them up makes an invisible position render as a glyph. This is the usual reason legacy systems show odd characters in some locales.
A code point is not a glyph
The Unicode basic plane reserves many code points purely for visual compatibility with existing characters, including 494 compatibility characters that collapse under normalization. U+2126 OHM SIGN normalises to U+03A9 GREEK CAPITAL OMEGA; the U+FB01 ligature expands to two letters. Any exact string comparison, deduplication or validation that skips normalisation will treat visually identical strings as different.
Mixing hexadecimal and decimal is the most common conversion slip
Code point 0x41 and 65 denote the same character A. Treating a hex value as decimal (or the reverse) yields an entirely unrelated character and raises no error, because the number itself is perfectly valid in JS. A good sanity check is the resulting string length: printable ASCII sits in 0x20-0x7E, so a decimal value outside that range is proof of a base mix-up somewhere.

How This Relates to Neighbours

For the byte structure and conversion relationships of GBK / Big5 / Shift-JIS / UTF-8, use the Character Encodings page; this one only covers the 7-bit 0-127 base range.

For code points, names and search across emoji and symbols, use the Emoji page, which is organised by code point rather than decimal.

Percent-encoding in URLs (%20, %E4%B8%AD) is a hexadecimal view of UTF-8 bytes — a different layer from character code points. Use the in-site URL encoding tools for that.

If the goal is debugging mojibake in production, the Character Encodings section on writer/reader encoding mismatch will locate the problem faster than any code point table.

Practical Snippet

Key points: (1) [...s] counts code points while s.length counts UTF-16 code units, so an emoji counts as 2 — any length limit gives a different verdict depending on which you use; (2) TextEncoder yields UTF-8 byte counts regardless of the real target encoding, so GBK needs separate calculation; (3) pair codePointAt with String.fromCodePoint and avoid charCodeAt, which returns only the leading surrogate half of a pair.

// 字符串的三个长度：字符 / 码点 / UTF-8 字节
const s = 'A中🛠'

// ① 码点数（用 [...s] 而非 s.length，emoji 会被算成 2）
const codePoints = [...s].length

// ② UTF-8 字节数（TextEncoder 按标准编码，中文 3 字节、emoji 4 字节）
const bytes = new TextEncoder().encode(s).length

// ③ 各层长度对照 —— ASCII 范围内三者一致，超出后迅速发散
console.log({ charLength: s.length, codePoints, bytes })

// 码点 ↔ 字符：用 codePointAt 而非 charCodeAt（后者取不到代理对的后半）
const back = String.fromCodePoint(0x1f6e0)  // 🛠
const cp = back.codePointAt(0)

/* 典型结果：
  { charLength: 5, codePoints: 3, bytes: 8 }
  charLength 用 UTF-16 计数单位，中文 1、emoji 2，所以是 5；
  码点 3（'A'、'中'、'🛠'）；UTF-8 字节 1+3+4 = 8。
  ⇒ 涉及长度上限（DB 字段、协议头）时必须明确用哪一种口径。 */

Practical Notes

CRLF vs LF causes phantom blank linesWindows text uses CRLF (13, 10) while Unix uses LF (10). Read a CRLF file as Unix and every line ends with a stray \r, so $ anchors fail to match and string comparisons differ. Normalize line endings at the boundary.
Control characters must be escaped in JSON and URLsCode points 0–31 become \u0000–\u001f in JSON and percent-encoded in URLs (a tab is %09). Inlining them raw makes parsers error out or truncate the message, which happens constantly in log pipelines.
DEL (127) is not printableIt sits in the control range, is usually invisible in a terminal, and still consumes one byte. Visible-length counters must exclude 0–31 and 127 or they overcount, and input validation should reject those code points explicitly.

Data Sources

ANSI X3.4-1986
ISO/IEC 646
Unicode Standard (C0/C1 controls)

Codes, names and definitions above come from public specifications; we claim no originality over the specification data itself. The arrangement, Chinese annotations and practical notes on this page are written by us.

DEC	HEX	Char	Name	Chinese Name
0	0x00	NUL	Null	空字符
1	0x01	SOH	Start of Heading	标题开始
2	0x02	STX	Start of Text	正文开始
3	0x03	ETX	End of Text	正文结束
4	0x04	EOT	End of Transmission	传输结束
5	0x05	ENQ	Enquiry	询问
6	0x06	ACK	Acknowledge	确认
7	0x07	BEL	Bell	响铃
8	0x08	BS	Backspace	退格
9	0x09	HT	Horizontal Tab	水平制表
10	0x0A	LF	Line Feed	换行
11	0x0B	VT	Vertical Tab	垂直制表
12	0x0C	FF	Form Feed	换页
13	0x0D	CR	Carriage Return	回车
14	0x0E	SO	Shift Out	移出
15	0x0F	SI	Shift In	移入
16	0x10	DLE	Data Link Escape	数据链路转义
17	0x11	DC1	Device Control 1	设备控制1
18	0x12	DC2	Device Control 2	设备控制2
19	0x13	DC3	Device Control 3	设备控制3
20	0x14	DC4	Device Control 4	设备控制4
21	0x15	NAK	Negative Acknowledge	否定确认
22	0x16	SYN	Synchronous Idle	同步空闲
23	0x17	ETB	End of Trans. Block	传输块结束
24	0x18	CAN	Cancel	取消
25	0x19	EM	End of Medium	介质结束
26	0x1A	SUB	Substitute	替换
27	0x1B	ESC	Escape	转义
28	0x1C	FS	File Separator	文件分隔符
29	0x1D	GS	Group Separator	组分隔符
30	0x1E	RS	Record Separator	记录分隔符
31	0x1F	US	Unit Separator	单元分隔符
32	0x20	SP	Space	空格
33	0x21	!	Exclamation Mark	感叹号
34	0x22	"	Quotation Mark	双引号
35	0x23	#	Number Sign	井号
36	0x24	$	Dollar Sign	美元符号
37	0x25	%	Percent Sign	百分号
38	0x26	&	Ampersand	与号
39	0x27	'	Apostrophe	单引号
40	0x28	(	Left Parenthesis	左括号
41	0x29	)	Right Parenthesis	右括号
42	0x2A	*	Asterisk	星号
43	0x2B	+	Plus Sign	加号
44	0x2C	,	Comma	逗号
45	0x2D	-	Hyphen	连字符
46	0x2E	.	Period	句点
47	0x2F	/	Slash	斜杠
48	0x30	0	Digit Zero	数字 0
49	0x31	1	1	1
50	0x32	2	2	2
51	0x33	3	3	3
52	0x34	4	4	4
53	0x35	5	5	5
54	0x36	6	6	6
55	0x37	7	7	7
56	0x38	8	8	8
57	0x39	9	Digit Nine	数字 9
58	0x3A	:	:	:
59	0x3B	;	;	;
60	0x3C	<	<	<
61	0x3D	=	=	=
62	0x3E	>	>	>
63	0x3F	?	?	?
64	0x40	@	@	@
65	0x41	A	Uppercase A	大写 A
66	0x42	B	B	B
67	0x43	C	C	C
68	0x44	D	D	D
69	0x45	E	E	E
70	0x46	F	F	F
71	0x47	G	G	G
72	0x48	H	H	H
73	0x49	I	I	I
74	0x4A	J	J	J
75	0x4B	K	K	K
76	0x4C	L	L	L
77	0x4D	M	M	M
78	0x4E	N	N	N
79	0x4F	O	O	O
80	0x50	P	P	P
81	0x51	Q	Q	Q
82	0x52	R	R	R
83	0x53	S	S	S
84	0x54	T	T	T
85	0x55	U	U	U
86	0x56	V	V	V
87	0x57	W	W	W
88	0x58	X	X	X
89	0x59	Y	Y	Y
90	0x5A	Z	Uppercase Z	大写 Z
91	0x5B	[	[	[
92	0x5C	\	\	\
93	0x5D	]	]	]
94	0x5E	^	^	^
95	0x5F	_	_	_
96	0x60	`	`	`
97	0x61	a	Lowercase a	小写 a
98	0x62	b	b	b
99	0x63	c	c	c
100	0x64	d	d	d
101	0x65	e	e	e
102	0x66	f	f	f
103	0x67	g	g	g
104	0x68	h	h	h
105	0x69	i	i	i
106	0x6A	j	j	j
107	0x6B	k	k	k
108	0x6C	l	l	l
109	0x6D	m	m	m
110	0x6E	n	n	n
111	0x6F	o	o	o
112	0x70	p	p	p
113	0x71	q	q	q
114	0x72	r	r	r
115	0x73	s	s	s
116	0x74	t	t	t
117	0x75	u	u	u
118	0x76	v	v	v
119	0x77	w	w	w
120	0x78	x	x	x
121	0x79	y	y	y
122	0x7A	z	Lowercase z	小写 z
123	0x7B	{	{	{
124	0x7C	\|	\|	\|
125	0x7D	}	}	}
126	0x7E	~	~	~
127	0x7F	DEL	Delete	删除

Frequently Asked Questions

What is ASCII?

ASCII (American Standard Code for Information Interchange) uses 7 bits to represent 128 characters including letters, digits, punctuation and control characters — the most basic character encoding.

How is ASCII related to Unicode?

ASCII covers only 128 characters; Unicode is a superset that is compatible with the first 128 ASCII code points and extends to every writing system. UTF-8 is an ASCII-compatible Unicode encoding.

What are control characters?

Code points 0-31 and 127 are control characters (e.g. LF, CR, Tab) that are not printable; they are used for device control and text formatting.

Why represent ASCII in hex?

Hexadecimal is more compact and readable than binary or decimal (0x41 = "A"), and is most common when debugging protocols and parsing messages.

How do I look up the ASCII code of a character?

Find the character in the Char column of the table above; the DEC value on its left is the ASCII code and HEX is the hexadecimal form. For example "A" is 65 (0x41), the space (SP) is 32 (0x20), and line feed (LF) is 10 (0x0A).