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Binary to Octal Converter

Type any binary number and instantly see its octal, 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 Binary to Octal Converter?

Binary is the base-2 number system using only 0 and 1. Octal is the base-8 number system using digits 0–7.

Like hex and binary, octal has a clean mapping to binary: every group of exactly 3 binary bits maps to one octal digit (since 8 = 2³):

- 000 → 0 - 001 → 1 - 111 → 7

For example, 11001010 binary splits into groups of 3 from the right: 011 001 010 = 3 1 2 = 312 octal.

Octal is most commonly encountered in Unix/Linux file permissions. The familiar `chmod 755` means: 7 (rwx) for owner, 5 (r-x) for group, 5 (r-x) for others. In binary: 111 101 101.

How to Use Binary to Octal Converter

1

Type or paste a binary number into the input field (digits 0 and 1 only)

2

The octal, decimal, and hexadecimal equivalents appear instantly

3

Click any "Copy" button to copy a specific result

4

Click "Load Sample" to see an example conversion

Common Use Cases

  • Converting binary Unix permission bits (e.g. 111101101) to chmod octal values (755).
  • Translating binary output from legacy systems that used octal notation.
  • Verifying binary-to-octal conversions in computer science coursework.
  • Converting binary sensor or register values to octal for old embedded system documentation.
  • Understanding how 3-bit groups in binary map cleanly to single octal digits.

Example Input and Output

The binary number 11001010 is converted to octal 312, decimal 202, and hex CA.

Binary input
11001010
Octal equivalent
312 (octal) = 202 (decimal) = CA (hex)

Privacy

All number conversions run in your browser using JavaScript BigInt. No data is sent to any server.

Unix permissions example

chmod 755 in binary: 7 = 111 (owner rwx), 5 = 101 (group r-x), 5 = 101 (others r-x) → binary 111101101. Paste 111101101 here to verify.

Frequently Asked Questions

How do I convert binary to octal manually?

Group your binary number into chunks of 3 bits from the right (pad with leading zeros if needed). Convert each group: 000=0, 001=1, 010=2, 011=3, 100=4, 101=5, 110=6, 111=7. Concatenate the octal digits. Example: 11001010 → 011 001 010 → 3 1 2 → 312.

Why does octal relate cleanly to binary?

Because 8 = 2³, exactly 3 binary bits map to one octal digit. This is similar to how 4 bits map to one hex digit. Binary-to-octal conversion can be done by grouping bits into triplets, with no arithmetic needed.

Can I enter binary numbers with the 0b prefix?

Yes. The tool accepts both plain binary (1010) and the 0b-prefixed format (0b1010) used in JavaScript, Python, and C.

Where is octal still used today?

Octal is primarily used in Unix/Linux file permission notation (chmod 755), and occasionally in embedded systems documentation, C string octal escapes (\012 = newline), and some legacy minicomputer architectures.

How large a binary number can this handle?

This tool uses JavaScript BigInt, which handles arbitrarily large integers with no precision loss.

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