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Octal Converter

Convert octal numbers to and from decimal, binary, and hexadecimal. Essential for Unix file permissions, assembly programming, and computer science.

Used 37.1K times today

Enter any value to convert between all number bases.

0o
0b
0x

How to Use Octal Converter

  1. 1

    Enter an octal value

    Type an octal number (digits 0–7 only) into the input field.

  2. 2

    Choose the conversion direction

    Select whether you want to convert the octal input to decimal, binary, or hexadecimal.

  3. 3

    View the result

    The converted value appears instantly alongside all other base representations.

Frequently Asked Questions

What is octal and when is it used?
Octal is a base-8 number system using digits 0–7. It is widely used in Unix/Linux file permissions (e.g., chmod 755) and in certain assembly languages and embedded systems programming.
What digits are valid in octal?
Only digits 0 through 7 are valid in octal. The digit 8 or 9 would indicate an error in your octal input.
How do Unix file permissions use octal?
Each permission group (owner, group, others) is represented by three bits, giving values 0–7 per group. For example, 755 means owner has full access (7), group and others have read and execute (5).

About Octal Converter

The Octal Converter on Utilko is particularly valuable for developers and system administrators who work with Unix and Linux environments. Octal notation is the standard way to express file permission codes with the chmod command, making it one of the most practically useful number-base tools in a developer's toolkit.

Beyond file permissions, octal appears in legacy computing systems, certain microcontroller instruction sets, and low-level data encoding. This converter lets you move between octal, decimal, binary, and hexadecimal instantly, removing the mental overhead of manual base conversion.

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