Convert octal to binary (base 8 → base 2)
Use this converter when you have octal integers (base 8) and need the binary representation (base 2).
This page is a focused Octal → Binary variant built for speed:
- Batch mode is enabled by default (one value per line)
- Controls are intentionally hidden to keep this variant fast and distraction-free
Need decimal/hex too, swapping, or formatting options? Open the full Number Base Converter.
How to use it
- Paste your octal values into the input (left).
- Use one number per line.
- Copy the binary results from the output (right).
Signed values are supported:
-11→-1001+377→11111111
Input rules (octal)
Allowed digits
Octal input may contain only:
- digits
0–7 - an optional leading
+or-
Examples:
0710755-52
Optional 0o prefix
You may paste values like:
0o755-0o52
Separators are ignored
Spaces and underscores are ignored, so these are valid:
7_550o7 55
Output format (binary)
- Output is a binary integer using
0and1 - Negative values keep a leading
- - No
0bprefix by default
Examples:
10→100011→100152→101010377→111111112000→10000000000-52→-101010
Quick mental check (3-bit mapping)
Octal maps cleanly to binary because each octal digit equals 3 bits:
5(octal) →101(binary)2(octal) →010(binary)
So:
52(octal) →101 010(binary) →101010
You don’t need to do this manually — the converter does it — but it’s a helpful way to sanity-check results.
Batch example (one per line)
Input (octal):
10
11
52
377
-52
0o755
8Output (binary):
1000
1001
101010
11111111
-101010
111101101
!ERROR: Octal input may contain only digits 0–7One invalid line won’t break the rest.
Common use cases
Permissions and bit fields
Octal is often used for permission masks because it aligns with binary bits. Converting to binary makes the underlying bit pattern obvious.
Embedded systems and digital logic
Octal is compact but still binary-friendly, which is useful when inspecting registers or bitmasks.
Learning number bases
Octal → binary is one of the clearest demonstrations of how different bases represent the same value.
Troubleshooting
“Octal input may contain only digits 0–7”
A line includes an invalid digit (like 8 or 9).
Remove invalid characters, or switch bases in the full tool if your input isn’t actually octal.
“Should the output be padded?”
This converter outputs the minimal binary representation.
If you need fixed widths (like 8/16/32-bit), pad the output on the left with zeros as needed.
Notes
- This is number base conversion for integers, not text/byte encoding.
- Everything runs locally in your browser — nothing is uploaded.
