How many characters are in ASCII?

128, numbered 0 to 127, of which 33 are control characters — 0 to 31 plus DEL at 127 — and 95 are printable, counting the space. Anything numbered above 127 is not ASCII: it belongs to whatever code page or encoding is in use, which is why the same byte shows as é, ‚ or † depending on where the file is opened.

Why is DEL 127 rather than 0?

Because ASCII was designed for paper tape. 127 is 1111111 — every bit set — so a character could be deleted by punching out all seven holes over whatever was already there. There was no way to un-punch a hole, so the delete code had to be the one that overwrites everything.

Is the space a control character?

No. Space is code 32 and is the first printable character; it simply has no ink. DEL at 127 is the control character that sits above every graphic one. Hand-written tables regularly get both backwards.

What is the difference between ASCII and UTF-8?

For the first 128 codes, nothing — UTF-8 encodes them as a single byte with the same value, which is why ASCII text is valid UTF-8 unchanged. Above 127 they diverge completely: UTF-8 uses two to four bytes and covers every script, while ASCII stops.

Why is the difference between A and a exactly 32?

Because 32 is bit 5, and the alphabet was laid out so that case is a single bit. A is 1000001 and a is 1100001, so changing case is one XOR — which is how every C library implemented toupper for thirty years.

ASCII table

ASCII has 128 codes, 0 to 127: 33 control characters and 95 printable ones, with the space at 32 counted among the printable. Capital A is 65 and lower-case a is 97, so the case bit is the difference of 32 — a single bit, which is why toggling case was once a bitwise operation rather than a lookup.

All 128 codes in decimal, hex, octal and binary, with every control character named and the escape sequence a C-family language writes it as. 95 are printable and 33 are control codes — and the two that surprise people are that the space is in the first group and DEL is in the second.

Codes checked against RFC 20 and the Unicode Basic Latin chart 16 August 2026 · How we check

Printable characters, 32 to 126

Printable characters, 32 to 126
Char	Dec	Hex	Oct	Binary
space	32	20	040	0100000
!	33	21	041	0100001
"	34	22	042	0100010
#	35	23	043	0100011
$	36	24	044	0100100
%	37	25	045	0100101
&	38	26	046	0100110
'	39	27	047	0100111
(	40	28	050	0101000
)	41	29	051	0101001
*	42	2A	052	0101010
+	43	2B	053	0101011
,	44	2C	054	0101100
-	45	2D	055	0101101
.	46	2E	056	0101110
/	47	2F	057	0101111
0	48	30	060	0110000
1	49	31	061	0110001
2	50	32	062	0110010
3	51	33	063	0110011
4	52	34	064	0110100
5	53	35	065	0110101
6	54	36	066	0110110
7	55	37	067	0110111
8	56	38	070	0111000
9	57	39	071	0111001
:	58	3A	072	0111010
;	59	3B	073	0111011
<	60	3C	074	0111100
=	61	3D	075	0111101
>	62	3E	076	0111110
?	63	3F	077	0111111
@	64	40	100	1000000
A	65	41	101	1000001
B	66	42	102	1000010
C	67	43	103	1000011
D	68	44	104	1000100
E	69	45	105	1000101
F	70	46	106	1000110
G	71	47	107	1000111
H	72	48	110	1001000
I	73	49	111	1001001
J	74	4A	112	1001010
K	75	4B	113	1001011
L	76	4C	114	1001100
M	77	4D	115	1001101
N	78	4E	116	1001110
O	79	4F	117	1001111
P	80	50	120	1010000
Q	81	51	121	1010001
R	82	52	122	1010010
S	83	53	123	1010011
T	84	54	124	1010100
U	85	55	125	1010101
V	86	56	126	1010110
W	87	57	127	1010111
X	88	58	130	1011000
Y	89	59	131	1011001
Z	90	5A	132	1011010
[	91	5B	133	1011011
\	92	5C	134	1011100
]	93	5D	135	1011101
^	94	5E	136	1011110
_	95	5F	137	1011111
`	96	60	140	1100000
a	97	61	141	1100001
b	98	62	142	1100010
c	99	63	143	1100011
d	100	64	144	1100100
e	101	65	145	1100101
f	102	66	146	1100110
g	103	67	147	1100111
h	104	68	150	1101000
i	105	69	151	1101001
j	106	6A	152	1101010
k	107	6B	153	1101011
l	108	6C	154	1101100
m	109	6D	155	1101101
n	110	6E	156	1101110
o	111	6F	157	1101111
p	112	70	160	1110000
q	113	71	161	1110001
r	114	72	162	1110010
s	115	73	163	1110011
t	116	74	164	1110100
u	117	75	165	1110101
v	118	76	166	1110110
w	119	77	167	1110111
x	120	78	170	1111000
y	121	79	171	1111001
z	122	7A	172	1111010
{	123	7B	173	1111011
\|	124	7C	174	1111100
}	125	7D	175	1111101
~	126	7E	176	1111110

Control characters, 0 to 31 and 127

None of these has a glyph. Most are dead conventions from teleprinters and paper tape; about six are still load-bearing in software written today.

Control characters, 0 to 31 and 127
Dec	Hex	Name	Escape	Still matters because
0	00	NUL — null	\0	Ends a string in C. A byte of zero, not the digit 0.
1	01	SOH — start of heading
2	02	STX — start of text
3	03	ETX — end of text
4	04	EOT — end of transmission
5	05	ENQ — enquiry
6	06	ACK — acknowledge
7	07	BEL — bell	\a	Rang the teleprinter bell. Terminals still beep on it.
8	08	BS — backspace	\b
9	09	HT — horizontal tab	\t
10	0A	LF — line feed	\n	A newline on Unix and macOS. Windows writes CR LF, which is why a file moved between them grows or shrinks by one byte a line.
11	0B	VT — vertical tab	\v
12	0C	FF — form feed	\f	A page break to a printer.
13	0D	CR — carriage return	\r	Returns to column one without advancing. Alone it is a classic mangled-file symptom.
14	0E	SO — shift out
15	0F	SI — shift in
16	10	DLE — data link escape
17	11	DC1 — device control 1
18	12	DC2 — device control 2
19	13	DC3 — device control 3
20	14	DC4 — device control 4
21	15	NAK — negative acknowledge
22	16	SYN — synchronous idle
23	17	ETB — end of block
24	18	CAN — cancel
25	19	EM — end of medium
26	1A	SUB — substitute
27	1B	ESC — escape	\e	Opens an ANSI escape sequence — every terminal colour starts here.
28	1C	FS — file separator
29	1D	GS — group separator
30	1E	RS — record separator
31	1F	US — unit separator
127	7F	DEL — delete		Not a control code by position: it is all bits set, which is what punching out every hole on a paper tape produced.

Questions people actually ask

How many characters are in ASCII?: 128, numbered 0 to 127, of which 33 are control characters — 0 to 31 plus DEL at 127 — and 95 are printable, counting the space. Anything numbered above 127 is not ASCII: it belongs to whatever code page or encoding is in use, which is why the same byte shows as é, ‚ or † depending on where the file is opened.
Why is DEL 127 rather than 0?: Because ASCII was designed for paper tape. 127 is 1111111 — every bit set — so a character could be deleted by punching out all seven holes over whatever was already there. There was no way to un-punch a hole, so the delete code had to be the one that overwrites everything.
Is the space a control character?: No. Space is code 32 and is the first printable character; it simply has no ink. DEL at 127 is the control character that sits above every graphic one. Hand-written tables regularly get both backwards.
What is the difference between ASCII and UTF-8?: For the first 128 codes, nothing — UTF-8 encodes them as a single byte with the same value, which is why ASCII text is valid UTF-8 unchanged. Above 127 they diverge completely: UTF-8 uses two to four bytes and covers every script, while ASCII stops.
Why is the difference between A and a exactly 32?: Because 32 is bit 5, and the alphabet was laid out so that case is a single bit. A is 1000001 and a is 1100001, so changing case is one XOR — which is how every C library implemented toupper for thirty years.

Cite this page

APA: Rule Calculator. (2026). ASCII Table. Rule Calculator. https://rulecalculators.com/ascii-table
MLA: "ASCII Table." Rule Calculator, August 16, 2026, https://rulecalculators.com/ascii-table.
Chicago: Rule Calculator. "ASCII Table." Rule Calculator. Last reviewed August 16, 2026. https://rulecalculators.com/ascii-table.

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Sources

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