Octal to Decimal Converter
Convert octal numbers to decimal, including fractions and negative numbers, with the working shown.
Change the values and press Calculate to work out your own figures.
Enter a octal number to write it in decimal.
Show the working
- 755₈ = 7 × 8² + 5 × 8¹ + 5 × 8⁰ = 493
How to use it
Enter a octal number to write it in decimal.
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
octal → decimal: place values Σ dᵢ × bⁱ; repeated division by the new base
How the conversion works
To decimal, multiply each digit by its place value (a power of the base) and add; from decimal, divide by the base repeatedly and read the remainders from the bottom up (for a fraction, multiply by the base and read off the whole parts).
Questions
What is 755 in decimal?
493.
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
octal → decimal: place values Σ dᵢ × bⁱ; repeated division by the new base
Sources
Limitations
- Numbers have at most 1,000 characters; Roman numerals cover whole numbers from 1 to 3,999,999.