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Binary to Octal Converter
Convert any binary number to octal instantly — see how the bits group into threes. Free, fast, no sign-up.
Only 0s and 1s allowed — spaces, commas and dashes are ignored.
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Also equals
- Binary
- Decimal
- Octal
- Hex
Step-by-step calculation
| 3-bit group | Octal digit |
|---|
How to convert binary to octal
- Split the binary number into groups of 3 bits, starting from the right (pad the left with zeros if needed).
- Convert each 3-bit group to its octal digit (000=0 … 111=7).
- Read the digits left to right — that's your octal number.
Example: 101101₂ → 101 101 → 5 5 → 55₈.
Background reading: the octal number system on Wikipedia.
Conversion table
Binary 0000–1111 grouped in threes, with the resulting octal digit.
| Binary | Octal | Grouping (3 bits each) |
|---|---|---|
| 0000 | 0 | 000 000 → 0₈ |
| 0001 | 1 | 000 001 → 1₈ |
| 0010 | 2 | 000 010 → 2₈ |
| 0011 | 3 | 000 011 → 3₈ |
| 0100 | 4 | 000 100 → 4₈ |
| 0101 | 5 | 000 101 → 5₈ |
| 0110 | 6 | 000 110 → 6₈ |
| 0111 | 7 | 000 111 → 7₈ |
| 1000 | 10 | 001 000 → 10₈ |
| 1001 | 11 | 001 001 → 11₈ |
| 1010 | 12 | 001 010 → 12₈ |
| 1011 | 13 | 001 011 → 13₈ |
| 1100 | 14 | 001 100 → 14₈ |
| 1101 | 15 | 001 101 → 15₈ |
| 1110 | 16 | 001 110 → 16₈ |
| 1111 | 17 | 001 111 → 17₈ |
| 111111 | 77 | 111 111 → 77₈ = 63 |
Powers of 2
| Power | Value |
|---|---|
| 20 | 1 |
| 21 | 2 |
| 22 | 4 |
| 23 | 8 |
| 24 | 16 |
| 25 | 32 |
| 26 | 64 |
| 27 | 128 |
| 28 | 256 |
| 29 | 512 |
| 210 | 1024 |
| 211 | 2048 |
| 212 | 4096 |
| 213 | 8192 |
| 214 | 16384 |
| 215 | 32768 |
| 216 | 65536 |
Binary to octal in code
Python
oct(int("1010", 2))[2:] # → '12'JavaScript
parseInt("1010", 2).toString(8); // → '12'C
#include <stdio.h>
#include <stdlib.h>
int main(void) {
long v = strtol("1010", NULL, 2); /* → 10 */
printf("%lo\n", v); /* → 12 */
return 0;
}Common values
1010₂ =12₈111₂ =7₈111111₂ =77₈1000₂ =10₈0₂ =0₈101011₂ =53₈
Key takeaways
- Group bits in threes from the right, then convert each group.
- Pad the left with zeros so the bits divide evenly into threes.
- 1010₂ = 12₈; 11111111₂ = 377₈.
- It works because 8 = 2³ — one octal digit per three bits.
Frequently asked questions
How do I convert binary to octal?
Group the bits in threes from the right, convert each group to an octal digit, and read the digits left to right.
What is 1010 in octal?
1010₂ = 12₈.
Why group in threes?
Because 2³ = 8 — each group of 3 bits maps exactly to one octal digit.
What is 1010 in octal?
Group in 3s from the right: 001 010 → 12₈.
Why group binary digits in threes for octal?
Because 8 = 2³ — each octal digit represents exactly three binary bits.
What is 11111111 in octal?
Group in 3s: 011 111 111 → 377₈ = 255.
Do I need to pad with leading zeros?
Yes — pad the left with zeros so the bits divide evenly into groups of three (for example 1010 → 001010).
Need the reverse? Try our octal to binary converter.