Octal to Binary Converter

Convert octal numbers to binary by expanding each octal digit into its three-bit equivalent with a step-by-step breakdown.

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Enter a valid octal number Please enter an octal number to convert.

Also in Number Theory

Number Systems

Octal to binary: convert base-8 numbers to base-2

The octal to binary converter translates octal (base-8) numbers into their binary (base-2) equivalents. Enter an octal value and see the binary result with each octal digit expanded to its three-bit representation.

How octal-to-binary conversion works

Each octal digit maps to exactly three binary digits. Replace each octal digit with its three-bit binary equivalent and concatenate the groups to form the full binary number.

For example, octal 75 becomes 111 101 in binary. The digit 7 maps to 111 and 5 maps to 101.

Practical applications

This conversion is particularly useful when analysing Unix file permissions at the bit level. Each permission digit (such as 7 for rwx) expands to three bits that represent read, write, and execute flags individually.

Frequently asked questions

Do I always get three bits per octal digit?

Yes. Every octal digit maps to exactly three binary bits, including leading zeros (for example, octal 1 becomes 001).

Can octal digits be 8 or 9?

No. Octal uses only digits 0 through 7. The digits 8 and 9 are invalid in base 8.

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