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Binary to Octal
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// about this tool

Binary to Octal Online

Updated 2026-10-24

Convert binary to octal online for free. Paste a binary value and SnapTools shows its octal representation instantly, right in your browser. Nothing you enter is uploaded.

Grouping bits by 3 instead of 4 is what turns raw binary into octal instead of hex, and it's the grouping Unix permissions rely on, since a value like 111101101 reads as three clean 3-bit permission triplets once it's in octal (755). This converter handles the grouping and padding for you, so you get a compact, correct octal value from any binary string. For every base at once, use the Number Base Converter.

// how to use

  1. 1 Paste or type a binary value into the input, using digits 0 and 1 only.
  2. 2 SnapTools converts it to octal as you type.
  3. 3 Copy the octal result, or open the Number Base Converter for all bases at once.

// examples

Permission-style bits
Input
111101101
Output
755
Byte value
Input
11111111
Output
377

// common uses

Turning raw permission bits back into a chmod-style octal value Compacting a long binary string into fewer, denser digits Checking a manual binary-to-octal conversion Learning how binary groups map to octal digits

// faq

Why did some early computers group bits into octal instead of hex?
The PDP-8, built by Digital Equipment Corporation and one of the first commercially successful minicomputers, used a 12-bit word, which splits evenly into four 3-bit octal digits but not into whole 4-bit hex digits. That word size, not convention alone, is why octal rather than hex was the natural notation on many 1960s machines.
How do I convert binary to octal by hand?
Working right to left, break the bit string into threes, padding the final leftover chunk with zeros, and each 3-bit chunk is one octal digit between 0 and 7. Rather than counting bit positions by hand, this tool splits and reads the chunks for you.
Why group binary in 3s instead of 4s?
Groups of 4 give you hex; groups of 3 give you octal. Octal grouping is what you want when the result needs to read as a Unix permission value like 755, since each 3-bit group is exactly one permission triplet.
Does my binary value need to be a multiple of 3 bits long?
No, this tool pads the leftmost group automatically, so any length of binary input converts correctly.
What if my input has a character other than 0 or 1?
Only 0 and 1 are legal in a binary string, so a stray character of any other kind gets caught by validation and flagged for you to fix, rather than being silently converted into a misleading result.

// works with your data

Octal to Binary Binary to Hex Binary to Decimal Number Base Converter Decimal to Octal LLM Token Counter

Use this via API

Get a free API key → 
curl -X POST https://thesnaptools.com/api/v1/tools/binary-to-octal \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"number":"111101101"}'