ASCII Binary Reference Table - Complete 0-127 Binary Chart

ASCII Binary Quick Reference

I have built and referenced countless ASCII-to-binary tables over the years, and I always come back to the same appreciation: ASCII's design is beautifully systematic. Every uppercase letter differs from its lowercase counterpart by exactly one bit (bit 5). Digits 0 through 9 occupy codes 48-57, meaning you can convert '0' to binary by writing 0110000 plus the digit value. Once you internalize these patterns, manual binary decoding becomes almost as fast as reading plain text.

Control Characters (0-31)

The first 32 ASCII codes are control characters — they do not print anything but control how data is interpreted. Here is what each one means:

Dec	Hex	Binary (7-bit)	Binary (8-bit)	Char
0	0x00	0000000	00000000	NUL
1	0x01	0000001	00000001	SOH
2	0x02	0000010	00000010	STX
3	0x03	0000011	00000011	ETX
4	0x04	0000100	00000100	EOT
5	0x05	0000101	00000101	ENQ
6	0x06	0000110	00000110	ACK
7	0x07	0000111	00000111	BEL
8	0x08	0001000	00001000	BS
9	0x09	0001001	00001001	TAB
10	0x0A	0001010	00001010	LF
11	0x0B	0001011	00001011	VT
12	0x0C	0001100	00001100	FF
13	0x0D	0001101	00001101	CR
14	0x0E	0001110	00001110	SO
15	0x0F	0001111	00001111	SI
16	0x10	0010000	00010000	DLE
17	0x11	0010001	00010001	DC1
18	0x12	0010010	00010010	DC2
19	0x13	0010011	00010011	DC3
20	0x14	0010100	00010100	DC4
21	0x15	0010101	00010101	NAK
22	0x16	0010110	00010110	SYN
23	0x17	0010111	00010111	ETB
24	0x18	0011000	00011000	CAN
25	0x19	0011001	00011001	EM
26	0x1A	0011010	00011010	SUB
27	0x1B	0011011	00011011	ESC
28	0x1C	0011100	00011100	FS
29	0x1D	0011101	00011101	GS
30	0x1E	0011110	00011110	RS
31	0x1F	0011111	00011111	US

Key point: Control characters like LF (10, line feed) and CR (13, carriage return) are critical for understanding text file formats. Windows uses CR+LF (00001101 00001010), while Unix uses just LF (00001010). This difference causes the classic "mixed line endings" problem.

Printable Characters (32-127)

Codes 32-126 are the printable characters. Code 127 is DEL. Here is the full table:

Dec	Hex	Binary (7-bit)	Binary (8-bit)	Char
32	0x20	0100000	00100000	[Space]
33	0x21	0100001	00100001	!
34	0x22	0100010	00100010	"
35	0x23	0100011	00100011	#
36	0x24	0100100	00100100	$
37	0x25	0100101	00100101	%
38	0x26	0100110	00100110	&
39	0x27	0100111	00100111	'
40	0x28	0101000	00101000	(
41	0x29	0101001	00101001	)
42	0x2A	0101010	00101010	*
43	0x2B	0101011	00101011	+
44	0x2C	0101100	00101100	,
45	0x2D	0101101	00101101	-
46	0x2E	0101110	00101110	.
47	0x2F	0101111	00101111	/
48	0x30	0110000	00110000	0
49	0x31	0110001	00110001	1
50	0x32	0110010	00110010	2
51	0x33	0110011	00110011	3
52	0x34	0110100	00110100	4
53	0x35	0110101	00110101	5
54	0x36	0110110	00110110	6
55	0x37	0110111	00110111	7
56	0x38	0111000	00111000	8
57	0x39	0111001	00111001	9
58	0x3A	0111010	00111010	:
59	0x3B	0111011	00111011	;
60	0x3C	0111100	00111100	<
61	0x3D	0111101	00111101	=
62	0x3E	0111110	00111110	>
63	0x3F	0111111	00111111	?
64	0x40	1000000	01000000	@
65	0x41	1000001	01000001	A
66	0x42	1000010	01000010	B
67	0x43	1000011	01000011	C
68	0x44	1000100	01000100	D
69	0x45	1000101	01000101	E
70	0x46	1000110	01000110	F
71	0x47	1000111	01000111	G
72	0x48	1001000	01001000	H
73	0x49	1001001	01001001	I
74	0x4A	1001010	01001010	J
75	0x4B	1001011	01001011	K
76	0x4C	1001100	01001100	L
77	0x4D	1001101	01001101	M
78	0x4E	1001110	01001110	N
79	0x4F	1001111	01001111	O
80	0x50	1010000	01010000	P
81	0x51	1010001	01010001	Q
82	0x52	1010010	01010010	R
83	0x53	1010011	01010011	S
84	0x54	1010100	01010100	T
85	0x55	1010101	01010101	U
86	0x56	1010110	01010110	V
87	0x57	1010111	01010111	W
88	0x58	1011000	01011000	X
89	0x59	1011001	01011001	Y
90	0x5A	1011010	01011010	Z
91	0x5B	1011011	01011011	[
92	0x5C	1011100	01011100	\
93	0x5D	1011101	01011101	]
94	0x5E	1011110	01011110	^
95	0x5F	1011111	01011111	_
96	0x60	1100000	01100000	`
97	0x61	1100001	01100001	a
98	0x62	1100010	01100010	b
99	0x63	1100011	01100011	c
100	0x64	1100100	01100100	d
101	0x65	1100101	01100101	e
102	0x66	1100110	01100110	f
103	0x67	1100111	01100111	g
104	0x68	1101000	01101000	h
105	0x69	1101001	01101001	i
106	0x6A	1101010	01101010	j
107	0x6B	1101011	01101011	k
108	0x6C	1101100	01101100	l
109	0x6D	1101101	01101101	m
110	0x6E	1101110	01101110	n
111	0x6F	1101111	01101111	o
112	0x70	1110000	01110000	p
113	0x71	1110001	01110001	q
114	0x72	1110010	01110010	r
115	0x73	1110011	01110011	s
116	0x74	1110100	01110100	t
117	0x75	1110101	01110101	u
118	0x76	1110110	01110110	v
119	0x77	1110111	01110111	w
120	0x78	1111000	01111000	x
121	0x79	1111001	01111001	y
122	0x7A	1111010	01111010	z
123	0x7B	1111011	01111011	{
124	0x7C	1111100	01111100	\|
125	0x7D	1111101	01111101	}
126	0x7E	1111110	01111110	~
127	0x7F	1111111	01111111	DEL

The Uppercase-Lowercase Bit Pattern

One of my favorite ASCII design details is how uppercase and lowercase letters relate at the binary level:

A = 1000001 (65), a = 1100001 (97)
The difference is exactly bit 5 (value 32)
Uppercase has bit 5 = 0, lowercase has bit 5 = 1
Toggling bit 5 flips between cases: A (65) XOR 32 = a (97)

This means you can convert between cases with a single bitwise XOR operation. This is not just a curiosity — old terminal protocols used this property to implement case-insensitive matching without string comparison.

7-Bit vs 8-Bit Binary

The ASCII table above shows both 7-bit and 8-bit binary representations. Here is why both matter:

7-bit binary covers the original ASCII standard (0-127, fitting in 7 bits)
8-bit binary pads each code with a leading 0 to fill a full byte
Extended ASCII (128-255) uses the 8th bit for additional characters — but these are not standardized and vary by code page

When using a binary to text converter, you will most often see 8-bit sequences, since computers work with bytes. But understanding the 7-bit foundation helps you recognize that the leading bit in standard ASCII should always be 0.

Using This Table with Binary Tools

This reference table pairs perfectly with our binary translator tools. When you use the binary decoder, you can cross-reference the binary output against this table to verify your results. The pattern I recommend: look at the binary output, identify the first 4 bits (high nibble) and last 4 bits (low nibble), then find the character in the table. With practice, you will start recognizing common characters by their binary patterns alone — 01000001 is always 'A', 01100001 is always 'a'.