Decimal to Octal Converter
Convert decimal numbers to octal (base 8) and back. Used in Unix file permissions and early computing.
Reviewed October 7, 2026 Runs in your browser — inputs are never stored
Octal
377
This tool provides general unit conversions for everyday and educational use. For regulated, legal, or scientific applications, verify conversion factors against the applicable official standard.
About the Decimal to Octal Converter
The decimal to octal converter changes base-10 numbers into octal (base 8) by repeated division by 8, and converts octal back to decimal. Octal is most often met in Unix and Linux file permissions such as 755 and 644.
How to use it
- 1Choose decimal → octal or octal → decimal.
- 2Enter the number.
- 3Read the result.
- 4Copy, share or print the result with the buttons below it.
Worked example
255 ÷ 8 = 31 remainder 7; 31 ÷ 8 = 3 remainder 7; 3 ÷ 8 = 0 remainder 3, so 255 = 377 in octal.
How it works
Method
Divide the decimal number by 8 repeatedly; remainders give the octal digits. Example: 255 ÷ 8 = 31 R7; 31 ÷ 8 = 3 R7; 3 ÷ 8 = 0 R3 → 377 octal.
Common use cases
- Setting Unix file permissions
- Computer science homework
- Legacy system programming
Frequently asked questions
A:255 decimal = 377 octal.
A:Octal is used in Unix/Linux file permissions (chmod 755 = rwxr-xr-x) and in some older hardware interfaces.
Reviewed for accuracy · Last updated October 7, 2026
Conversion factors are based on internationally defined SI units and standard metric/imperial equivalence tables.
CalcWisee Editorial Team
Calculator development and formula review
CalcWisee is an independent site founded by Ayman. Every calculator is built from a published formula or official definition, tested against hand-worked examples before it goes live, and corrected promptly when a reader reports an issue to ayman@calcwisee.com.
Expertise: Financial mathematics, Health and fitness formulas, Applied mathematics, Unit conversion standards
References & sources
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