Convert binary to octal as you type, with every step shown. This free online converter gives exact results for numbers of any size, and nothing you type leaves your browser.
1 Enter your value
From
To
0x
Examples
2 Your answer
Decimal
dec
Show in other bases
Tap any value to copy it.
See the working
Guide
How it works
Three steps, whether you are reading a memory address, a bit flag or a byte value.
1
Choose what to convert
Pick what you have and what you want: decimal, hexadecimal, binary or octal.
2
Type or paste a value
Write it however you like: 65,535, 0xFF, FFh, with commas, spaces or underscores.
3
Read the answer
It appears as you type, in every other base, with the working shown.
The formulas
A digit's value depends on its position. Every answer here uses one of these rules:
Binary to octal
group the bits in threes from the right
0b110100011 → 110 100 011 → 6, 4, 3, so 0b110100011 is 0o643.
Octal to binary
each octal digit = 3 binary bits
0o643 is 6 → 110, 4 → 100, 3 → 011, so 0o643 is 110 100 011.
Binary to decimal
decimal = Σ digit × 2position
0b110100011 is 1 × 256 + 1 × 128 + 1 × 32 + 1 × 2 + 1 × 1 = 419, so the answer checks out.
Decimal to hexadecimal digit chart
The decimal values 0 to 15 are the single hexadecimal digits 0 to F. Click one to add it to the converter.
All conversions
Decimal, hexadecimal, binary and octal converter
One free tool for every direction. Use it as a decimal to hexadecimal converter, convert decimal to binary or octal, or work backwards as a hexadecimal to decimal converter that turns 0x to decimal values. It also converts hexadecimal to binary, binary to hexadecimal and octal to decimal, so it works as a full number base converter and hexadecimal calculator. Pick a conversion to start.
Each octal digit stands for exactly 3 binary bits. Split the binary number into groups of 3 bits, starting from the right, and pad the leftmost group with zeros.
Replace each group with its octal digit.
Worked example
0b110100011 → 110 100 011
→ 6 4 3
= 0o643
Binary to Octal conversion table
Use this binary to octal table as a quick binary to octal chart for common values, from 0 to 65,535.
Binary
Octal
0
0
1
1
10
2
11
3
100
4
101
5
110
6
111
7
1000
10
1001
11
1010
12
1011
13
1100
14
1101
15
1110
16
1111
17
1 0000
20
10 0000
40
100 0000
100
110 0100
144
111 1111
177
1000 0000
200
1111 1111
377
1 0000 0000
400
10 0000 0000
1000
11 1110 1000
1750
100 0000 0000
2000
1 0000 0000 0000
10000
1111 1111 1111 1111
177777
Help
Questions
Quick answers to what people most often ask about hexadecimal, decimal and binary.
01How do I convert binary to octal?
Each octal digit stands for exactly 3 binary bits. Split the binary number into groups of 3 bits, starting from the right, and pad the leftmost group with zeros. Replace each group with its octal digit.
02What is 11111111 in octal?
0b11111111 in binary is 0o377 in octal (255 in decimal). Type 11111111 into the converter above to see every step.
03What is 10000000000 in octal?
0b10000000000 in binary is 0o2000 in octal (1,024 in decimal).
04What is 1010 in octal?
0b1010 in binary is 0o12 in octal (10 in decimal).
05What is 1111 in octal?
0b1111 in binary is 0o17 in octal (15 in decimal).
06What is 10000000 in octal?
0b10000000 in binary is 0o200 in octal (128 in decimal). It is a byte with only its top bit set.
07Why is one octal digit exactly three binary bits?
Because 8 = 2³. Three bits can hold 8 different values, 000 to 111, which is exactly the range of one octal digit, 0 to 7. So 0o777 is 111 111 111 in binary.
08How do I convert binary to octal in Excel?
Use the BIN2OCT function: =BIN2OCT("11111111") returns 377. It works the same way in Google Sheets. These functions only handle up to 10 input characters, and the binary ones only −512 to 511, so use this converter for larger numbers.
09How do I convert binary to octal in Python or JavaScript?
In Python, oct(int('11111111', 2)) returns '0o377'. In JavaScript, parseInt('11111111', 2).toString(8) returns '377'. Python handles any size; in JavaScript use BigInt for numbers above 2⁵³.
10Does the converter use two’s complement for negative numbers?
No. It keeps the minus sign, so −255 is −0xFF, −0b11111111 and −0o377. Computers usually store negative numbers in two’s complement, where the pattern depends on the width: −1 is 1111 1111 (0xFF) in 8 bits and 0xFFFF in 16 bits. To read a signed value whose top bit is set, subtract 2ⁿ: 0xFF as a signed 8-bit number is 255 − 256 = −1.
11Can I convert binary numbers with a fractional part?
The converter works with whole numbers. By hand, convert the fractional part by multiplying it by the target base again and again and keeping the whole-number part each time. For example, 0.5 × 16 = 8, so 0.5 is 0x0.8 in hexadecimal, 0b0.1 in binary and 0o0.4 in octal.
12How many bits are in a byte?
Eight. A byte holds 0 to 255, which is 0000 0000 to 1111 1111 in binary, 0x00 to 0xFF in hexadecimal and 0o000 to 0o377 in octal.
13Is there a limit to how big a binary number can be?
No. The converter uses exact whole-number arithmetic, so 64-bit, 128-bit and longer binary values convert to octal with every digit correct, with no rounding.
14What does “bin to oct” mean?
“bin to oct” is short for binary to octal, which means going from base 2 to base 8: a number written in base 2 is rewritten in base 8. For example, 0b11111111 becomes 0o377.
15Does this binary to octal calculator show the working?
Yes. It converts binary to octal with steps: open “See the working” under the answer to see each digit multiplied by its power of 2, then the result written in octal. Every answer is also shown in decimal, hexadecimal, binary and octal at once.
16Is this binary to octal converter free?
Yes. It is free with no sign-up, works online on phones, tablets and computers, and every binary to octal conversion runs in your browser, so nothing you type is sent anywhere.