Binary to Octal Converter: Base 2 to Base 8

Binary to Octal Converter

Convert between binary and octal numbers

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The binary system (base 2) uses only digits 0 and 1, and is the language computers use internally. The octal system (base 8) uses digits 0–7, and groups binary digits into sets of three for a more compact representation.

For example, the binary number 1010 equals 12 in octal (1×8 + 0×4 + 1×2 + 0×1 = 10 in decimal, which is 12 in octal). Type in either field below and the other updates instantly.

Binary

Octal

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Quick Reference (all bases)

Octal is less common today than hexadecimal but still appears in specific contexts like Unix file permissions, this converter switches between binary and octal instantly.

How to use this binary to octal converter

Enter a value in the Binary field to see the equivalent in octal.
Or enter a value in the Octal field to see the equivalent in binary, either field updates the other instantly.

What this converter does

The binary system (base 2) uses only digits 0 and 1, the language computers use internally. The octal system (base 8) uses digits 0-7, and groups binary digits into sets of three for a more compact representation than raw binary.

1010 (binary) = 12 (octal), since 1010 in binary is 10 in decimal, which is 12 in octal

Why octal groups binary digits in threes

Because 8 is a power of 2 (2³), each octal digit corresponds to exactly 3 binary digits, making octal-to-binary conversion a matter of simple grouping rather than a full base conversion, similar to how hexadecimal groups binary digits in sets of 4.

Where octal is still used today

Octal’s most common surviving use is Unix and Linux file permission notation, where a permission set like 755 represents read/write/execute permissions for owner, group, and others, each digit derived from a 3-bit binary pattern of read/write/execute flags.

Frequently asked questions

Where is octal still used today?

Its most common modern use is Unix/Linux file permission notation (like chmod 755), where each octal digit represents a 3-bit combination of read/write/execute permissions.

How do I convert binary to octal?

Group the binary digits into sets of 3 starting from the right, then convert each group directly to its octal digit (0-7), since 8 is a power of 2, this avoids needing a full decimal conversion step.