Octal to Decimal Converter

Convert octal numbers to decimal instantly. Transform base-8 values used in Unix permissions and programming into standard decimal notation.

Common Unix Permissions

How to Use

  1. Enter an octal number (0-7 digits)
  2. Decimal value appears instantly
  3. View optional step breakdown
  4. Copy the decimal result

Features

  • Instant octal to decimal conversion
  • Handles any octal length
  • Unix permission calculator
  • Real-time conversion
  • Shows calculation steps
  • Validates octal input

About This Tool


Octal (base-8) uses digits 0-7 and was historically important in computing. Today, it's still used for Unix/Linux file permissions and some programming contexts.

The conversion works like other base conversions: each position represents a power of 8. Multiply each digit by its position value (8^0, 8^1, 8^2...) and sum the results.

For example, octal 755 = 7×8² + 5×8¹ + 5×8⁰ = 448 + 40 + 5 = 493 in decimal. In Unix, 755 represents rwxr-xr-x permissions.

Our converter is particularly useful for system administrators and developers working with Unix permissions. Enter permission values like 644, 755, or 777 to see their decimal equivalents.

Understanding octal helps when working with older systems, embedded programming, or any context where this number system is still in use.

Frequently Asked Questions

Why is octal used for Unix permissions?
Each permission group (owner, group, others) uses 3 bits, which maps perfectly to a single octal digit (0-7).
What does octal 777 mean?
Octal 777 = decimal 511, granting read(4)+write(2)+execute(1) = 7 permissions to owner, group, and others.
Why only digits 0-7?
Octal is base-8, so it uses 8 digits (0-7), just as decimal uses 10 (0-9) and binary uses 2 (0-1).
How is octal written in code?
Many programming languages use leading 0 (like 0755) or 0o (like 0o755) to indicate octal numbers.
Is octal still relevant today?
While less common than hex, octal remains important for Unix/Linux permissions and some legacy systems.

Convert octal numbers to decimal instantly. Transform base-8 values used in Unix permissions and programming into standard decimal notation.

Key Features

  • Instant octal to decimal conversion
  • Handles any octal length
  • Unix permission calculator
  • Real-time conversion
  • Shows calculation steps
  • Validates octal input

How to Use This Tool

  1. Enter an octal number (0-7 digits)
  2. Decimal value appears instantly
  3. View optional step breakdown
  4. Copy the decimal result
Octal (base-8) uses digits 0-7 and was historically important in computing. Today, it's still used for Unix/Linux file permissions and some programming contexts. The conversion works like other base conversions: each position represents a power of 8. Multiply each digit by its position value (8^0, 8^1, 8^2...) and sum the results. For example, octal 755 = 7×8² + 5×8¹ + 5×8⁰ = 448 + 40 + 5 = 493 in decimal. In Unix, 755 represents rwxr-xr-x permissions. Our converter is particularly useful for system administrators and developers working with Unix permissions. Enter permission values like 644, 755, or 777 to see their decimal equivalents. Understanding octal helps when working with older systems, embedded programming, or any context where this number system is still in use.

Benefits

  • Understand Unix permissions
  • Convert legacy octal values
  • Programming applications
  • Learn number systems

Frequently Asked Questions

Why is octal used for Unix permissions?

Each permission group (owner, group, others) uses 3 bits, which maps perfectly to a single octal digit (0-7).

What does octal 777 mean?

Octal 777 = decimal 511, granting read(4)+write(2)+execute(1) = 7 permissions to owner, group, and others.

Why only digits 0-7?

Octal is base-8, so it uses 8 digits (0-7), just as decimal uses 10 (0-9) and binary uses 2 (0-1).

How is octal written in code?

Many programming languages use leading 0 (like 0755) or 0o (like 0o755) to indicate octal numbers.

Is octal still relevant today?

While less common than hex, octal remains important for Unix/Linux permissions and some legacy systems.

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