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Octal to Binary Converter
Free online Octal to Binary Converter for 2026. Convert octal numbers to binary and binary to octal instantly — also shows decimal and hex equivalents. 100% browser-based.
Enter octal values (digits 0–7) one per line or space-separated.
Octal and Binary — A Natural Fit
Octal (base-8) uses digits 0–7. Each octal digit maps perfectly to exactly 3 binary bits — making conversion between the two systems purely a lookup with zero arithmetic. Octal 7 = binary 111, octal 5 = binary 101.
Octal is most commonly seen in Unix/Linux file permissions — the familiar chmod 755 is octal. Each digit encodes one 3-bit permission triplet: read (4), write (2), execute (1).
chmod 755 decoded:
7
111 = rwx (owner)
5
101 = r-x (group)
5
101 = r-x (other)
Octal ↔ Binary Reference Table
0
000
1
001
2
010
3
011
4
100
5
101
6
110
7
111
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Frequently Asked Questions
How do I convert octal to binary?
Each octal digit (0–7) maps directly to a 3-bit binary group. Octal 7 = binary 111, octal 5 = binary 101. Octal 57 becomes 101 111.
What is octal used for?
Octal is most commonly used for Unix/Linux file permissions (e.g. chmod 755). Each octal digit encodes one 3-bit permission triplet: read (4), write (2), and execute (1).
What is octal 755 in binary?
Octal 755 in binary is 111 101 101. This represents the Unix permission
rwxr-xr-x — full access for the owner, read+execute for group and others.Can I convert binary to octal?
Yes. Switch to the Binary to Octal tab. Binary digits are grouped into triplets from right to left, each mapped to its octal digit.
Does this show decimal and hex too?
Yes. Each result line shows the binary output alongside its decimal and hexadecimal equivalents so you can compare all four number systems at once.
What is octal 7 in binary?
Octal 7 is binary 111 — all three bits set to 1. It is the largest single octal digit and equals decimal 7.
Is my data safe?
Yes. All conversion runs entirely in your browser. Nothing is sent to any server.