Octal Converter — Convert Octal to Binary, Decimal, and Hex

Octal is base 8. Digits 0 through 7. If you have used chmod 755, you have used octal.

Convert Octal Instantly

1. Open the Number Base Converter
2. Select Octal (Base 8)
3. Type your number (digits 0-7)
4. Get binary, decimal, and hex simultaneously

Octal to Binary (3-Bit Substitution)

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

Octal 752: 7→111, 5→101, 2→010 = 111101010 (490 decimal).

Octal to Decimal

Octal 752: 7×64 + 5×8 + 2×1 = 448 + 40 + 2 = 490

Decimal to Octal

490: 490÷8=61r2, 61÷8=7r5, 7÷8=0r7. Read bottom to top: 752.

Linux File Permissions

Permission	Bit	Meaning
r (read)	4	View contents
w (write)	2	Modify
x (execute)	1	Run or enter directory

Common permissions:

Octal	Binary	Symbolic	Meaning
755	111 101 101	rwxr-xr-x	Owner full. Group/others read+execute.
644	110 100 100	rw-r--r--	Owner read/write. Others read only.
700	111 000 000	rwx------	Owner only.
777	111 111 111	rwxrwxrwx	Full access for everyone. Avoid this.
600	110 000 000	rw-------	Owner read/write. Good for SSH keys.

Octal Bug in C/C++

• int x = 010; is octal 10 = decimal 8, not 10
• int y = 0755; = decimal 493
• int z = 099; = compiler error (9 invalid in octal)

Octal to Hex

Go through binary: 752 → 111 101 010 → regroup: 0001 1110 1010 → 1EA hex.

Related: Base64 Encoder, JSON Formatter.