Binary to Octal Converter
Convert binary numbers to octal, including fractions and negative numbers, with the working shown.
Change the values and press Calculate to work out your own figures.
Enter a binary number to write it in octal.
Show the working
- Group the bits in 3s from the right: 010 101 010
- Replace each group with its octal digit: 2 5 2
How to use it
Enter a binary number to write it in octal.
Letters stand for digits above 9 (A = 10 … Z = 35) and can be typed in either case; prefixes such as 0b and 0x, spaces and underscores are ignored. Show the working gives each step.
Key facts
binary → octal: regroup the bits (3 per octal digit, 4 per hex digit)
How the conversion works
Because 8 = 2³ and 16 = 2⁴, each octal digit is exactly 3 bits and each hex digit exactly 4, so the conversion is done by grouping bits.
Questions
What is 10101010 in octal?
252.
Can I convert fractions?
Yes. Digits after the point are converted exactly; if they repeat forever in the new base, the repeating block is shown in parentheses.
Formulas
binary → octal: regroup the bits (3 per octal digit, 4 per hex digit)
Sources
Limitations
- Numbers have at most 1,000 characters; Roman numerals cover whole numbers from 1 to 3,999,999.