Octal to Decimal Converter

Convert any octal number to decimal (base-10), binary and hexadecimal — with the positional value method shown step by step.

What Does This Tool Do?

Convert octal numbers to decimal using the positional value method — each digit multiplied by 8 raised to its position. Also shows binary and hex equivalents.

Key Features

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3 Outputs
Decimal, binary and hex.
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Positional Steps
Each digit × 8^n shown.
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Live
Updates as you type.
✅
Validates Input
Warns if non-octal digits entered.

How to Use

  1. Enter an octal number (digits 0–7). The 0o prefix is stripped automatically.
  2. Decimal, binary and hex appear instantly.
  3. Read the positional steps to learn the conversion.

Frequently Asked Questions

How do you convert octal to decimal?▾
Multiply each digit by 8 raised to its position from the right (starting at 0), then sum. E.g. 377 = 3×64 + 7×8 + 7×1 = 192 + 56 + 7 = 255.
Where is octal used today?▾
Unix/Linux file permissions use octal (chmod 755 = rwxr-xr-x). Each octal digit represents 3 permission bits. Octal was also used in PDP-11 and IBM mainframe systems.
How do I convert octal to binary?▾
Replace each octal digit with its 3-bit binary equivalent. E.g. 7 = 111, 5 = 101, so 75 (octal) = 111 101 (binary). This tool does it automatically.