Octal to decimal converter
Type an octal number such as 755 to see its decimal value and how it is worked out.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter octal number.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Multiply each digit by 8 raised to its position and add the results: power 0 for the rightmost whole digit, rising by 1 to the left, and -1, -2 after the point. Example: 17 = 1×8 + 7×1 = 15.
Example
Inputs: Octal number = 755. Result: Result in decimal: 493.
755
493
Limits and caveats
- Negative numbers keep a minus sign in front of the magnitude; they are not shown in two's complement.
- Up to 2000 digits before the point and 200 after it.
Questions about this tool
How do I convert 755 to decimal?
7 × 64 + 5 × 8 + 5 × 1 = 448 + 40 + 5 = 493.
Where are octal numbers used?
In Linux and Unix file permissions, some older systems and languages that write 0o before the number.
What do digits after the point mean in octal?
The first is in eighths and the second in sixty-fourths, so 0.4 = 4/8 = 0.5.