Octal to Decimal Converter
Convert octal (base 8) numbers to decimal (base 10) with full positional weight calculations shown. Digits 0–7 only. Free, fast, and no sign-up needed.
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How to Convert Octal to Decimal
Multiply each octal digit by 8 raised to its position (starting from 0 on right). Sum all products.
Example: 755₈ (Linux chmod) 7 × 8² = 7 × 64 = 448 5 × 8¹ = 5 × 8 = 40 5 × 8â° = 5 × 1 = 5 Total = 448 + 40 + 5 = 493
Octal in Real Life
Octal appears in Linux permissions: chmod 755 (7=rwx owner, 5=r-x group, 5=r-x others), some microcontroller registers, and older IBM mainframe systems. Understanding octal is essential for any Unix/Linux system administrator.
Frequently Asked Questions
How do I convert octal to decimal?
Multiply each digit by 8â¿ (n=position from right starting at 0). Sum all. Example: 17₈ = 1×8 + 7 = 15.
What is octal 755 in decimal?
755₈ = 7×64 + 5×8 + 5×1 = 448 + 40 + 5 = 493. In chmod, 755 means rwxr-xr-x.
What is 377 in decimal?
377₈ = 3×64 + 7×8 + 7 = 192 + 56 + 7 = 255, which equals decimal 255 = hex FF.