Octal to Binary Converter

Type a Octal number and get Binary instantly — plus every other base at the same time.

From To Mode

Number

Every base updates as you type; click bits to toggle them. Digit separators (_, spaces) are allowed. In two's complement mode the binary/octal/hex rows show the bit pattern and the decimal row shows the signed value. Choose Text to convert ASCII/UTF-8 text to bytes in any base — or bytes back to text.

How to convert Octal to Binary

Every octal digit expands to exactly 3 binary bits, so conversion is a pure digit-by-digit translation: replace each digit with its 3-bit pattern (from the table below) and join the groups together. Leading zeros on the first group can be dropped.

Worked example

Convert 725 (octal) to binary:

Digit 7 → 111
Digit 2 → 010
Digit 5 → 101
Join the groups and drop leading zeros: 111010101

So 725 in octal is 111010101 in binary.

Octal to Binary conversion table

Octal	Binary
0	0
1	1
2	10
3	11
4	100
5	101
6	110
7	111
10	1000
11	1001
12	1010
13	1011
14	1100
15	1101
16	1110
17	1111

Frequently asked questions

Can this handle numbers larger than 64 bits?: Yes. Conversion runs on arbitrary-precision integers, so numbers of any length convert exactly. Many online converters silently lose precision above 2⁵³ (about 16 decimal digits) — this one doesn't.
How do I convert negative numbers?: A leading minus sign works in every base. For the bit-pattern view programmers usually want, switch the mode to two's complement at 8, 16, 32, or 64 bits — then binary, octal, and hex show the bit pattern while decimal shows the signed value.
Can I convert the other way, or to other bases?: Use the Binary to Octal converter, or just change the From/To dropdowns above — every common base is shown at once anyway, and a Text mode converts ASCII to bytes and back.

Need arithmetic rather than conversion — adding hex numbers, shifting bits, masking? Use the programmer's calculator.