How do you convert a decimal number to octal?

To convert decimal to octal, divide the number by 8 and record the remainder. Continue dividing the resulting quotient by 8 until it reaches 0, then read the remainders in reverse order.

What is the octal value of decimal 64?

The decimal number 64 converts to octal as 100.

Can I convert octal numbers back to decimal?

Yes. Switch the converter mode to Octal to Decimal, paste your base-8 value, and the tool will instantly compute the base-10 integer equivalent.

Is my data stored or transmitted to any server?

No. The entire conversion process executes 100% locally in your web browser using JavaScript. Zero data is transmitted to or stored on any server.

Decimal to Octal Converter: Base-10 to Base-8

Decimal to Octal Converter

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Tip: enter one number to see the division steps, 2's complement, binary, hex and chmod permissions. Several numbers (new line, space or comma), fractions like 10.625 and e notation like 5.72e2 also work.

Output Width Negative Fraction Group by 3 0o prefix

Output appears here

Tool Name	Explanation
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Hex to Text Converter	Decodes hexadecimal values back into plain, human-readable text.
Text to Octal Converter	Converts text into octal bytes with separator, digits, and prefix options.
Octal to Text Converter	Decodes octal byte sequences back into readable plain text.
Decimal to Binary Converter	Converts decimal numbers into binary with step-by-step logic and 2's complement.
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Hex to Binary Converter	Converts base-16 hexadecimal numbers directly into base-2 binary strings.
Binary to Hex Converter	Groups binary digits into 4-bit nibbles and converts them to hex digits.
Octal to Binary Converter	Converts base-8 octal values directly into equivalent binary groups.
Binary to Octal Converter	Groups binary bits in sets of three to convert directly into octal numbers.
Hex to Decimal Converter	Converts base-16 hexadecimal values into base-10 decimal numbers using positional values.
Decimal to Hex Converter	Converts base-10 decimal numbers into base-16 hexadecimal with steps and prefix options.
Hex to Octal Converter	Converts hexadecimal numbers into octal by mapping hex digits through binary equivalents.
Octal to Hex Converter	Converts base-8 octal numbers directly into base-16 hexadecimal representations.

Example 1: Convert 215 to Octal

Division by 8	Quotient	Remainder (Octal digit)	Digit #
215/8	26	7	0
26/8	3	2	1
3/8	0	3	2

Read the remainders from the last step to the first: 215 = 327 (3 x 64 + 2 x 8 + 7).

Example 2: Convert 493 to Octal

Division by 8	Quotient	Remainder (Octal digit)	Digit #
493/8	61	5	0
61/8	7	5	1
7/8	0	7	2

Read the remainders from the last step to the first: 493 = 755 (7 x 64 + 5 x 8 + 5), the chmod mode rwxr-xr-x.

Decimal 0-255 to Octal Table

Decimal	Octal	Binary (8-bit)	Hex
0	`000`	`00000000`	00
1	`001`	`00000001`	01
2	`002`	`00000010`	02
3	`003`	`00000011`	03
4	`004`	`00000100`	04
5	`005`	`00000101`	05
6	`006`	`00000110`	06
7	`007`	`00000111`	07
8	`010`	`00001000`	08
9	`011`	`00001001`	09
10	`012`	`00001010`	0A
11	`013`	`00001011`	0B
12	`014`	`00001100`	0C
13	`015`	`00001101`	0D
14	`016`	`00001110`	0E
15	`017`	`00001111`	0F
16	`020`	`00010000`	10
17	`021`	`00010001`	11
18	`022`	`00010010`	12
19	`023`	`00010011`	13
20	`024`	`00010100`	14
21	`025`	`00010101`	15
22	`026`	`00010110`	16
23	`027`	`00010111`	17
24	`030`	`00011000`	18
25	`031`	`00011001`	19
26	`032`	`00011010`	1A
27	`033`	`00011011`	1B
28	`034`	`00011100`	1C
29	`035`	`00011101`	1D
30	`036`	`00011110`	1E
31	`037`	`00011111`	1F
32	`040`	`00100000`	20
33	`041`	`00100001`	21
34	`042`	`00100010`	22
35	`043`	`00100011`	23
36	`044`	`00100100`	24
37	`045`	`00100101`	25
38	`046`	`00100110`	26
39	`047`	`00100111`	27
40	`050`	`00101000`	28
41	`051`	`00101001`	29
42	`052`	`00101010`	2A
43	`053`	`00101011`	2B
44	`054`	`00101100`	2C
45	`055`	`00101101`	2D
46	`056`	`00101110`	2E
47	`057`	`00101111`	2F
48	`060`	`00110000`	30
49	`061`	`00110001`	31
50	`062`	`00110010`	32
51	`063`	`00110011`	33
52	`064`	`00110100`	34
53	`065`	`00110101`	35
54	`066`	`00110110`	36
55	`067`	`00110111`	37
56	`070`	`00111000`	38
57	`071`	`00111001`	39
58	`072`	`00111010`	3A
59	`073`	`00111011`	3B
60	`074`	`00111100`	3C
61	`075`	`00111101`	3D
62	`076`	`00111110`	3E
63	`077`	`00111111`	3F
64	`100`	`01000000`	40
65	`101`	`01000001`	41
66	`102`	`01000010`	42
67	`103`	`01000011`	43
68	`104`	`01000100`	44
69	`105`	`01000101`	45
70	`106`	`01000110`	46
71	`107`	`01000111`	47
72	`110`	`01001000`	48
73	`111`	`01001001`	49
74	`112`	`01001010`	4A
75	`113`	`01001011`	4B
76	`114`	`01001100`	4C
77	`115`	`01001101`	4D
78	`116`	`01001110`	4E
79	`117`	`01001111`	4F
80	`120`	`01010000`	50
81	`121`	`01010001`	51
82	`122`	`01010010`	52
83	`123`	`01010011`	53
84	`124`	`01010100`	54
85	`125`	`01010101`	55
86	`126`	`01010110`	56
87	`127`	`01010111`	57
88	`130`	`01011000`	58
89	`131`	`01011001`	59
90	`132`	`01011010`	5A
91	`133`	`01011011`	5B
92	`134`	`01011100`	5C
93	`135`	`01011101`	5D
94	`136`	`01011110`	5E
95	`137`	`01011111`	5F
96	`140`	`01100000`	60
97	`141`	`01100001`	61
98	`142`	`01100010`	62
99	`143`	`01100011`	63
100	`144`	`01100100`	64
101	`145`	`01100101`	65
102	`146`	`01100110`	66
103	`147`	`01100111`	67
104	`150`	`01101000`	68
105	`151`	`01101001`	69
106	`152`	`01101010`	6A
107	`153`	`01101011`	6B
108	`154`	`01101100`	6C
109	`155`	`01101101`	6D
110	`156`	`01101110`	6E
111	`157`	`01101111`	6F
112	`160`	`01110000`	70
113	`161`	`01110001`	71
114	`162`	`01110010`	72
115	`163`	`01110011`	73
116	`164`	`01110100`	74
117	`165`	`01110101`	75
118	`166`	`01110110`	76
119	`167`	`01110111`	77
120	`170`	`01111000`	78
121	`171`	`01111001`	79
122	`172`	`01111010`	7A
123	`173`	`01111011`	7B
124	`174`	`01111100`	7C
125	`175`	`01111101`	7D
126	`176`	`01111110`	7E
127	`177`	`01111111`	7F
128	`200`	`10000000`	80
129	`201`	`10000001`	81
130	`202`	`10000010`	82
131	`203`	`10000011`	83
132	`204`	`10000100`	84
133	`205`	`10000101`	85
134	`206`	`10000110`	86
135	`207`	`10000111`	87
136	`210`	`10001000`	88
137	`211`	`10001001`	89
138	`212`	`10001010`	8A
139	`213`	`10001011`	8B
140	`214`	`10001100`	8C
141	`215`	`10001101`	8D
142	`216`	`10001110`	8E
143	`217`	`10001111`	8F
144	`220`	`10010000`	90
145	`221`	`10010001`	91
146	`222`	`10010010`	92
147	`223`	`10010011`	93
148	`224`	`10010100`	94
149	`225`	`10010101`	95
150	`226`	`10010110`	96
151	`227`	`10010111`	97
152	`230`	`10011000`	98
153	`231`	`10011001`	99
154	`232`	`10011010`	9A
155	`233`	`10011011`	9B
156	`234`	`10011100`	9C
157	`235`	`10011101`	9D
158	`236`	`10011110`	9E
159	`237`	`10011111`	9F
160	`240`	`10100000`	A0
161	`241`	`10100001`	A1
162	`242`	`10100010`	A2
163	`243`	`10100011`	A3
164	`244`	`10100100`	A4
165	`245`	`10100101`	A5
166	`246`	`10100110`	A6
167	`247`	`10100111`	A7
168	`250`	`10101000`	A8
169	`251`	`10101001`	A9
170	`252`	`10101010`	AA
171	`253`	`10101011`	AB
172	`254`	`10101100`	AC
173	`255`	`10101101`	AD
174	`256`	`10101110`	AE
175	`257`	`10101111`	AF
176	`260`	`10110000`	B0
177	`261`	`10110001`	B1
178	`262`	`10110010`	B2
179	`263`	`10110011`	B3
180	`264`	`10110100`	B4
181	`265`	`10110101`	B5
182	`266`	`10110110`	B6
183	`267`	`10110111`	B7
184	`270`	`10111000`	B8
185	`271`	`10111001`	B9
186	`272`	`10111010`	BA
187	`273`	`10111011`	BB
188	`274`	`10111100`	BC
189	`275`	`10111101`	BD
190	`276`	`10111110`	BE
191	`277`	`10111111`	BF
192	`300`	`11000000`	C0
193	`301`	`11000001`	C1
194	`302`	`11000010`	C2
195	`303`	`11000011`	C3
196	`304`	`11000100`	C4
197	`305`	`11000101`	C5
198	`306`	`11000110`	C6
199	`307`	`11000111`	C7
200	`310`	`11001000`	C8
201	`311`	`11001001`	C9
202	`312`	`11001010`	CA
203	`313`	`11001011`	CB
204	`314`	`11001100`	CC
205	`315`	`11001101`	CD
206	`316`	`11001110`	CE
207	`317`	`11001111`	CF
208	`320`	`11010000`	D0
209	`321`	`11010001`	D1
210	`322`	`11010010`	D2
211	`323`	`11010011`	D3
212	`324`	`11010100`	D4
213	`325`	`11010101`	D5
214	`326`	`11010110`	D6
215	`327`	`11010111`	D7
216	`330`	`11011000`	D8
217	`331`	`11011001`	D9
218	`332`	`11011010`	DA
219	`333`	`11011011`	DB
220	`334`	`11011100`	DC
221	`335`	`11011101`	DD
222	`336`	`11011110`	DE
223	`337`	`11011111`	DF
224	`340`	`11100000`	E0
225	`341`	`11100001`	E1
226	`342`	`11100010`	E2
227	`343`	`11100011`	E3
228	`344`	`11100100`	E4
229	`345`	`11100101`	E5
230	`346`	`11100110`	E6
231	`347`	`11100111`	E7
232	`350`	`11101000`	E8
233	`351`	`11101001`	E9
234	`352`	`11101010`	EA
235	`353`	`11101011`	EB
236	`354`	`11101100`	EC
237	`355`	`11101101`	ED
238	`356`	`11101110`	EE
239	`357`	`11101111`	EF
240	`360`	`11110000`	F0
241	`361`	`11110001`	F1
242	`362`	`11110010`	F2
243	`363`	`11110011`	F3
244	`364`	`11110100`	F4
245	`365`	`11110101`	F5
246	`366`	`11110110`	F6
247	`367`	`11110111`	F7
248	`370`	`11111000`	F8
249	`371`	`11111001`	F9
250	`372`	`11111010`	FA
251	`373`	`11111011`	FB
252	`374`	`11111100`	FC
253	`375`	`11111101`	FD
254	`376`	`11111110`	FE
255	`377`	`11111111`	FF

Powers of 2 in Octal

Power	Decimal	Octal
2^0	1	`1`
2^1	2	`2`
2^2	4	`4`
2^3	8	`10`
2^4	16	`20`
2^5	32	`40`
2^6	64	`100`
2^7	128	`200`
2^8	256	`400`
2^9	512	`1000`
2^10	1024	`2000`
2^11	2048	`4000`
2^12	4096	`10000`
2^13	8192	`20000`
2^14	16384	`40000`
2^15	32768	`100000`
2^16	65536	`200000`
2^17	131072	`400000`
2^18	262144	`1000000`
2^19	524288	`2000000`
2^20	1048576	`4000000`
2^21	2097152	`10000000`
2^22	4194304	`20000000`
2^23	8388608	`40000000`
2^24	16777216	`100000000`
2^25	33554432	`200000000`
2^26	67108864	`400000000`
2^27	134217728	`1000000000`
2^28	268435456	`2000000000`
2^29	536870912	`4000000000`
2^30	1073741824	`10000000000`
2^31	2147483648	`20000000000`
2^32	4294967296	`40000000000`

Powers of 8 in Octal

Power	Decimal	Octal
8^0	1	`1`
8^1	8	`10`
8^2	64	`100`
8^3	512	`1000`
8^4	4096	`10000`
8^5	32768	`100000`
8^6	262144	`1000000`
8^7	2097152	`10000000`
8^8	16777216	`100000000`
8^9	134217728	`1000000000`
8^10	1073741824	`10000000000`

Common Decimal Numbers in Octal

Number	Decimal	Octal	Binary
Subnet mask octet (/25)	128	`200`	`10000000`
Subnet mask octet (/26)	192	`300`	`11000000`
Subnet mask octet (/27)	224	`340`	`11100000`
Subnet mask octet (/28)	240	`360`	`11110000`
Subnet mask octet (/29)	248	`370`	`11111000`
Subnet mask octet (/30)	252	`374`	`11111100`
Subnet mask octet (/31)	254	`376`	`11111110`
Subnet mask octet (/24)	255	`377`	`11111111`
SSH port	22	`26`	`10110`
SMTP port	25	`31`	`11001`
DNS port	53	`65`	`110101`
HTTP port	80	`120`	`1010000`
HTTPS port	443	`673`	`110111011`
MySQL port	3306	`6352`	`110011101010`
PostgreSQL port	5432	`12470`	`1010100111000`
Alternate HTTP port	8080	`17620`	`1111110010000`
Loopback first octet	127	`177`	`1111111`
Private IP first octet (10.x.x.x)	10	`12`	`1010`
Private IP first octet (192.168.x.x)	192	`300`	`11000000`
Private IP second octet (192.168.x.x)	168	`250`	`10101000`
Ten	10	`12`	`1010`
One hundred	100	`144`	`1100100`
One thousand	1000	`1750`	`1111101000`
Max signed 8-bit	127	`177`	`1111111`
Max unsigned 8-bit	255	`377`	`11111111`
Values in a byte	256	`400`	`100000000`
One kibibyte	1024	`2000`	`10000000000`
Page size	4096	`10000`	`1000000000000`
Max signed 16-bit	32767	`77777`	`111111111111111`
Max unsigned 16-bit	65535	`177777`	`1111111111111111`
Values in 16 bits	65536	`200000`	`10000000000000000`
Max RGB hex FFFFFF	16777215	`77777777`	`111111111111111111111111`
Max signed 32-bit	2147483647	`17777777777`	`1111111111111111111111111111111`
Max unsigned 32-bit	4294967295	`37777777777`	`11111111111111111111111111111111`
Days from 1970 to 2000	10957	`25315`	`10101011001101`
ASCII letter A	65	`101`	`1000001`
ASCII letter a	97	`141`	`1100001`
ASCII digit 0	48	`60`	`110000`
ASCII space	32	`40`	`100000`
ASCII line feed	10	`12`	`1010`

Common chmod Modes: Decimal to Octal

Decimal	Octal mode	Symbolic	Use
493	755	`rwxr-xr-x`	Executables, directories
420	644	`rw-r--r--`	Regular files
511	777	`rwxrwxrwx`	Everyone full access
384	600	`rw-------`	Private file
448	700	`rwx------`	Private directory or script
436	664	`rw-rw-r--`	Group writable file
488	750	`rwxr-x---`	Group can read and run
416	640	`rw-r-----`	Group can read
292	444	`r--r--r--`	Read only for all
509	775	`rwxrwxr-x`	Group writable directory

Decimal Fractions in Octal

Decimal	Octal	Type
0.5	`0.4`	Exact
0.25	`0.2`	Exact
0.125	`0.1`	Exact
0.75	`0.6`	Exact
0.375	`0.3`	Exact
0.625	`0.5`	Exact
1.5	`1.4`	Exact
2.75	`2.6`	Exact
10.625	`12.5`	Exact
0.1	`0.06314631`	Repeats, cut at 8 digits
0.2	`0.14631463`	Repeats, cut at 8 digits
0.3	`0.23146314`	Repeats, cut at 8 digits
0.6	`0.46314631`	Repeats, cut at 8 digits
3.14159	`3.11037476`	Repeats, cut at 8 digits
2.71828	`2.55760462`	Repeats, cut at 8 digits

Negative Numbers in Two's Complement Octal

Decimal	Positive Octal	8-bit Two's Complement	16-bit Two's Complement	32-bit Two's Complement
-1	`1`	`377`	`177777`	`37777777777`
-2	`2`	`376`	`177776`	`37777777776`
-3	`3`	`375`	`177775`	`37777777775`
-5	`5`	`373`	`177773`	`37777777773`
-8	`10`	`370`	`177770`	`37777777770`
-10	`12`	`366`	`177766`	`37777777766`
-16	`20`	`360`	`177760`	`37777777760`
-32	`40`	`340`	`177740`	`37777777740`
-64	`100`	`300`	`177700`	`37777777700`
-100	`144`	`234`	`177634`	`37777777634`
-127	`177`	`201`	`177601`	`37777777601`
-128	`200`	`200`	`177600`	`37777777600`
-200	`310`	not in range	`177470`	`37777777470`
-255	`377`	not in range	`177401`	`37777777401`
-1000	`1750`	not in range	`176030`	`37777776030`

Technical Q&A / FAQ Matrix

Technical Developer Question	Exact Solution & Code Snippet
How do I convert decimal to octal in JavaScript?	`(493).toString(8)`
How do I convert decimal to octal in Python?	`format(493, 'o')`
How do I convert decimal to octal in Go?	`strconv.FormatInt(493, 8)`
How do I convert decimal to octal in Java?	`Integer.toOctalString(493)`
How do I convert decimal to octal in C#?	`Convert.ToString(493, 8)`
How do I convert decimal to octal in PHP?	`echo decoct(493);`
How do I convert decimal to octal in Rust?	`format!("{:o}", 493)`
How do I convert decimal to octal on Linux?	`printf '%o\n' 493`
How do I pad octal to 3 digits?	`JavaScript: (5).toString(8).padStart(3, '0'). Python: format(5, '03o'). Result: 005.`
How do I convert decimal to octal by hand?	`Divide the number by 8 repeatedly and write down each remainder. Read the remainders from bottom to top. For 493: 493/8=61 r5, 61/8=7 r5, 7/8=0 r7, so 755.`
How do I get a chmod mode from permissions?	`Add read 4, write 2 and execute 1 for each of owner, group and others. rwxr-xr-x is 7, 5, 5, so 755 in octal, which is 493 in decimal.`
What is the largest number in 8, 16 and 32 bits?	`Unsigned: 255 (377), 65535 (177777) and 4294967295 (37777777777). Signed two's complement: 127 (177), 32767 (77777) and 2147483647 (17777777777).`
How are negative numbers written in octal?	`With two's complement. -1 in 8 bits is 377, in 16 bits is 177777. For -5 in 8 bits: 005 inverted is 372, plus 1 is 373.`
How do I convert a decimal fraction to octal?	`Multiply the fraction by 8 repeatedly and write down the integer part each time. For 0.625: 0.625 x 8 = 5.0, so 0.5.`
Why is octal 0.1 not exact?	`Decimal 0.1 is 0.0631463146... in octal and never ends, so the tool cuts it at the chosen number of digits.`
How do I convert octal back to decimal?	`JavaScript: parseInt('755', 8). Python: int('755', 8). Result: 493.`