Octal Converter - Octal to Decimal & Binary Conversion

Convert between octal (base 8), decimal, binary, and hexadecimal. Perfect for Unix permissions, programming, and computer science education.

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Octal Reference

Octal	Binary	Decimal
0	000	0
1	001	1
2	010	2
3	011	3
4	100	4
5	101	5
6	110	6
7	111	7

Common Permissions

Octal	Symbolic	Use Case
`777`	rwxrwxrwx	Full access (dangerous)
`755`	rwxr-xr-x	Executables, directories
`644`	rw-r--r--	Regular files
`600`	rw-------	Private files
`700`	rwx------	Private directories
`664`	rw-rw-r--	Group-editable files
`775`	rwxrwxr-x	Group-editable dirs

Permission Bits Explained

r (4)	Read - view file contents or list directory
w (2)	Write - modify file or create/delete in directory
x (1)	Execute - run file or access directory contents

Each digit is sum of permissions: 7 = 4+2+1 (rwx), 5 = 4+1 (r-x), 6 = 4+2 (rw-)

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Frequently Asked Questions

Octal is base-8 numbering using digits 0-7. It was popular in early computing and is still used for Unix file permissions (chmod 755).

Each octal digit maps to exactly 3 binary digits: 0=000, 1=001, 2=010, 3=011, 4=100, 5=101, 6=110, 7=111. This makes conversion straightforward.

In Unix: 7=rwx (owner), 5=r-x (group), 5=r-x (others). 7 in binary is 111 (read+write+execute), 5 is 101 (read+execute).

Each permission bit (read, write, execute) maps perfectly to 3 bits, which is exactly one octal digit. It's more compact than binary and more meaningful than decimal for permissions.

Use 'chmod 644 filename' to set rw-r--r-- (owner can write, all can read). 755 gives rwxr-xr-x (owner can execute, all can read/execute). Calculate using the permission calculator.

644 = rw-r--r-- (group cannot write). 664 = rw-rw-r-- (group can write). The middle digit controls group permissions. Use 664 for files that need group collaboration.

Yes, primarily for Unix/Linux file permissions. While hexadecimal is more common for general computing, octal remains the standard for permission management in all Unix-like systems.

777 (rwxrwxrwx) gives everyone full access—avoid except in specific cases. 666 (rw-rw-rw-) lets anyone modify files. 755 and 644 are safer defaults.

Yes. Directories typically use 755 (rwxr-xr-x) so everyone can read/navigate but only owner can modify. The execute bit on directories means 'can enter/traverse'.

The leading digit sets special bits: setuid (4), setgid (2), sticky bit (1). For example, 4755 sets the setuid bit. Most common usage is three digits only.

Octal Converter - Octal to Decimal & Binary Conversion

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Octal Reference

Unix File Permissions (chmod)

Owner

Group

Others

Common Permissions

Permission Bits Explained

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