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Octal to Binary Converter

Enter an octal number to instantly see its binary, decimal, and hexadecimal equivalents.

Last updated: May 30, 2026

Client-Side Processing
Input Data Stays on Device
Instant Local Execution

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What is Octal to Binary Converter?

Octal (base 8) uses digits 0–7, with each octal digit representing exactly 3 binary bits. This tight relationship makes octal-to-binary conversion straightforward: replace each octal digit with its corresponding 3-bit binary group.

Octal digit → 3-bit binary: - 0 → 000, 1 → 001, 2 → 010, 3 → 011 - 4 → 100, 5 → 101, 6 → 110, 7 → 111

For example, octal 377: - 3 → 011, 7 → 111, 7 → 111 - Binary: 011111111 = 11111111 (leading zeros stripped) = 255 decimal

How to Use Octal to Binary Converter

1

Type or paste an octal number in the input field (digits 0–7 only).

2

The binary, decimal, and hex outputs are updated instantly.

3

Click any copy button to copy the result to your clipboard.

4

Click "Load Sample" to see an example.

Common Use Cases

  • Understanding Unix chmod permission bits (e.g. 755 → binary 111 101 101).
  • Converting octal values in embedded systems or legacy code to binary for bit inspection.
  • Computer science coursework on number base systems.

Example Input and Output

Octal 755 (the common Unix read/write/execute permission) converts to binary 111101101.

Octal
755
Binary
111101101

Data Privacy

All conversions run entirely in your browser. No data is sent to any server.

Frequently Asked Questions

Why does each octal digit map to 3 binary bits?
Because 8 = 2³. Each octal digit (0–7) can be expressed as exactly 3 binary digits (000–111), making the mapping clean and lossless.
What octal digits are valid?
Only digits 0 through 7. The digits 8 and 9 do not exist in base-8 notation.
Does this support large octal values?
Yes. BigInt is used internally, so there is no practical size limit.

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