Character Encoding

ASCII Table

Explore the 7-bit ASCII standard, search individual codes, and turn text into hexadecimal byte values. Learn where ASCII stops and how it differs from Unicode and UTF-8.

By The End Of This Lesson

Match an ASCII character with its decimal, hexadecimal, and binary code.
Distinguish a number from the text characters used to write it.
Recognise ASCII's limits and distinguish Unicode code points from UTF-8 bytes.

Why Character Encoding Matters

A stored number does not identify its meaning by itself. An encoding supplies a shared mapping between characters and numeric codes. Reading a text file or a packet therefore involves both the bytes and the rules used to interpret them.

Readable Text

ASCII assigns codes to English letters, digits, punctuation, and space. Case matters: uppercase A and lowercase a have different codes.

Control Characters

Codes such as tab, line feed, and carriage return affect text structure. They are not visible letters, but they still occupy positions in the data.

Worked Example: The Number 7 And The Character 7

The numeric value seven, represented as an unsigned byte, differs from the ASCII character used to write the digit "7". The table assigns that character decimal code 55. Its hexadecimal value is 37 because 3 × 16 + 7 = 55.

Numeric Value Seven

7₁₀ = 07₁₆ = 0000 0111₂

ASCII Character "7"

55₁₀ = 37₁₆ = 0011 0111₂

ASCII has seven-bit codes. When stored in eight-bit bytes, their leading bit is zero. The text 42 contains two characters, with ASCII bytes 34 32; it is not the single numeric byte 2A.

ASCII Text To Hex

Enter ASCII text to see one two-digit hexadecimal byte per character. Spaces and newlines also have codes. Non-ASCII characters must be removed before conversion or copying.

Text Input

Hex Output

Live conversion updates as you type.

Enter ASCII text to begin. Empty input has no bytes.

ASCII At A Glance

Control

0–31, 127

Non-printable codes, including DEL at 127, for control and text flow.

Printable

32-126

Letters, digits, punctuation, and space. Space is printable even though it has no visible mark.

Standard

7-bit

128 total codes forming the original common text encoding baseline.

Beyond ASCII: Unicode And UTF-8

ASCII cannot represent £ or emoji. Unicode assigns code points to a much wider set of characters; UTF-8 is a way to encode those code points as bytes. A code point written in hexadecimal is not necessarily the byte sequence stored in a UTF-8 file.

For example, £ has code point U+00A3 and UTF-8 bytes C2 A3. The grinning-face emoji has code point U+1F600 and UTF-8 bytes F0 9F 98 80. Neither has an ASCII code. ASCII characters retain their single-byte values in UTF-8.

This converter deliberately stays within ASCII. For the byte-encoding rules, see RFC 3629: UTF-8 definition.

Complete ASCII Table

Search by decimal code, hex value, character, or description.

Dec	Hex	Char	Description	Type
0	00	NUL	Null	control
1	01	SOH	Start of Heading	control
2	02	STX	Start of Text	control
3	03	ETX	End of Text	control
4	04	EOT	End of Transmission	control
5	05	ENQ	Enquiry	control
6	06	ACK	Acknowledge	control
7	07	BEL	Bell	control
8	08	BS	Backspace	control
9	09	HT	Horizontal Tab	control
10	0A	LF	Line Feed	control
11	0B	VT	Vertical Tab	control
12	0C	FF	Form Feed	control
13	0D	CR	Carriage Return	control
14	0E	SO	Shift Out	control
15	0F	SI	Shift In	control
16	10	DLE	Data Link Escape	control
17	11	DC1	Device Control 1	control
18	12	DC2	Device Control 2	control
19	13	DC3	Device Control 3	control
20	14	DC4	Device Control 4	control
21	15	NAK	Negative Acknowledge	control
22	16	SYN	Synchronous Idle	control
23	17	ETB	End of Transmission Block	control
24	18	CAN	Cancel	control
25	19	EM	End of Medium	control
26	1A	SUB	Substitute	control
27	1B	ESC	Escape	control
28	1C	FS	File Separator	control
29	1D	GS	Group Separator	control
30	1E	RS	Record Separator	control
31	1F	US	Unit Separator	control
32	20	SP	Space	printable
33	21	!	Exclamation mark	printable
34	22	"	Quotation mark	printable
35	23	#	Number sign	printable
36	24	$	Dollar sign	printable
37	25	%	Percent sign	printable
38	26	&	Ampersand	printable
39	27	'	Apostrophe	printable
40	28	(	Left parenthesis	printable
41	29	)	Right parenthesis	printable
42	2A	*	Asterisk	printable
43	2B	+	Plus sign	printable
44	2C	,	Comma	printable
45	2D	-	Hyphen	printable
46	2E	.	Period	printable
47	2F	/	Forward slash	printable
48	30	0	Digit 0	printable
49	31	1	Digit 1	printable
50	32	2	Digit 2	printable
51	33	3	Digit 3	printable
52	34	4	Digit 4	printable
53	35	5	Digit 5	printable
54	36	6	Digit 6	printable
55	37	7	Digit 7	printable
56	38	8	Digit 8	printable
57	39	9	Digit 9	printable
58	3A	:	Colon	printable
59	3B	;	Semicolon	printable
60	3C	<	Less than	printable
61	3D	=	Equals sign	printable
62	3E	>	Greater than	printable
63	3F	?	Question mark	printable
64	40	@	At sign	printable
65	41	A	Uppercase A	printable
66	42	B	Uppercase B	printable
67	43	C	Uppercase C	printable
68	44	D	Uppercase D	printable
69	45	E	Uppercase E	printable
70	46	F	Uppercase F	printable
71	47	G	Uppercase G	printable
72	48	H	Uppercase H	printable
73	49	I	Uppercase I	printable
74	4A	J	Uppercase J	printable
75	4B	K	Uppercase K	printable
76	4C	L	Uppercase L	printable
77	4D	M	Uppercase M	printable
78	4E	N	Uppercase N	printable
79	4F	O	Uppercase O	printable
80	50	P	Uppercase P	printable
81	51	Q	Uppercase Q	printable
82	52	R	Uppercase R	printable
83	53	S	Uppercase S	printable
84	54	T	Uppercase T	printable
85	55	U	Uppercase U	printable
86	56	V	Uppercase V	printable
87	57	W	Uppercase W	printable
88	58	X	Uppercase X	printable
89	59	Y	Uppercase Y	printable
90	5A	Z	Uppercase Z	printable
91	5B	[	Left bracket	printable
92	5C	\	Backslash	printable
93	5D	]	Right bracket	printable
94	5E	^	Caret	printable
95	5F	_	Underscore	printable
96	60	`	Grave accent	printable
97	61	a	Lowercase a	printable
98	62	b	Lowercase b	printable
99	63	c	Lowercase c	printable
100	64	d	Lowercase d	printable
101	65	e	Lowercase e	printable
102	66	f	Lowercase f	printable
103	67	g	Lowercase g	printable
104	68	h	Lowercase h	printable
105	69	i	Lowercase i	printable
106	6A	j	Lowercase j	printable
107	6B	k	Lowercase k	printable
108	6C	l	Lowercase l	printable
109	6D	m	Lowercase m	printable
110	6E	n	Lowercase n	printable
111	6F	o	Lowercase o	printable
112	70	p	Lowercase p	printable
113	71	q	Lowercase q	printable
114	72	r	Lowercase r	printable
115	73	s	Lowercase s	printable
116	74	t	Lowercase t	printable
117	75	u	Lowercase u	printable
118	76	v	Lowercase v	printable
119	77	w	Lowercase w	printable
120	78	x	Lowercase x	printable
121	79	y	Lowercase y	printable
122	7A	z	Lowercase z	printable
123	7B	{	Left brace	printable
124	7C	\|	Vertical bar	printable
125	7D	}	Right brace	printable
126	7E	~	Tilde	printable
127	7F	DEL	Delete	control

Practise Reading Encoded Text

Predict the hex bytes for A7, then test them above. Add a space between the characters and explain the new byte. Finally try £ and explain why an ASCII converter reports an error instead of inventing an ASCII code.

Reveal the practice answers

A7 becomes 41 37. With a space, A 7 becomes 41 20 37. The £ character is outside ASCII's range and needs another encoding, such as UTF-8.

Use Build the Byte to represent decimal 65. Check that its hex byte is 41, then find that code in the ASCII table. The same bits can represent a number or a character depending on how the data is interpreted.

Check Your Understanding

Try these without the converter or reference table. Check each answer to reveal its explanation.

1. What is the ASCII hexadecimal byte for the text character 7?

073770

Choose an answer before checking. You can change your choice and try again.

2. Which codes are non-printable ASCII control codes?

Only 0–31.0–31 and 127 (DEL).All codes from 32 to 127.

Choose an answer before checking. You can change your choice and try again.

3. Why does this ASCII converter reject £?

The character is invalid in every text encoding.It needs a three-digit decimal input instead.It is outside ASCII, although Unicode and UTF-8 can represent it.

Choose an answer before checking. You can change your choice and try again.