Octal To Decimal Converter
Enter the octal value to convert to decimal or Decimal to Octal.
Octal:
Octal (Base-8) uses digits 0-7. It was historically used in computing as a shorthand for binary (each octal digit = 3 binary digits).
Decimal:
Decimal (Base-10) is the universal number system for everyday calculations.
How to Convert Octal to Decimal — Formula:
Decimal = Σ(dᵢ × 8ⁱ) where dᵢ is each octal digit and i is its position from right.
Example: Octal 755 = (7×8²) + (5×8¹) + (5×8⁰) = 448 + 40 + 5 = 493 decimal.
Technical Details:
Unix file permissions use octal: 7=rwx (read+write+execute), 5=r-x (read+execute), 0=--- (no permissions). chmod 755 = rwxr-xr-x.
Octal To Decimal Converter:
Convert octal numbers to decimal. Octal is still used in Unix/Linux file permissions (e.g., chmod 755).
Binary ↔ Hex ↔ Octal: Grouping Relationship
Binary → Hex (group by 4 bits):
Binary → Octal (group by 3 bits):
Frequently Asked Questions
How do I convert Octal to Decimal?
Decimal = Σ(dᵢ × 8ⁱ) where dᵢ is each octal digit and i is its position from right.
What is the Octal number system?
Octal (Base-8) uses digits 0-7. It was historically used in computing as a shorthand for binary (each octal digit = 3 binary digits).
What is the Decimal number system?
Decimal (Base-10) is the universal number system for everyday calculations.
Where is Octal to Decimal conversion used?
Unix file permissions use octal: 7=rwx (read+write+execute), 5=r-x (read+execute), 0=--- (no permissions). chmod 755 = rwxr-xr-x.
Can I convert large octal numbers?
Yes. This converter handles numbers of any practical size. For very large numbers, the conversion is performed using arbitrary-precision arithmetic to ensure accuracy.