Octal Calculator
Convert a number between octal and decimal, in either direction.
- Free to use
- Accurate results
- No registration required
- Works on all devices
Enter a number and choose a direction to convert between octal and decimal.
Enter a decimal number, or an octal number using only digits 0-7, depending on the direction chosen below.
Your result
100
Result
AI explanation
Formula
Repeated division/multiplication by 8 to convert between decimal and octal place valuesWorked example
Decimal 64 to octal
| Field | Value |
|---|---|
| Value | 64 |
| Convert | from-decimal |
| Result | 100 |
Assumptions
- Only non-negative whole numbers are supported.
- Octal input must contain only the digits 0-7.
Frequently asked questions
How does octal (base 8) work?
Octal uses 8 digits, 0 through 7, with each position representing a power of 8.
Where is octal used?
Octal was historically common in computing (especially with older systems using word sizes divisible by 3 bits) and is still used for Unix/Linux file permission notation (like chmod 755).
How is octal related to binary?
Each octal digit corresponds to exactly 3 binary digits (bits), making octal a compact shorthand for binary values, similar to how hex maps to 4-bit groups.