Decimal to Octal Converter
Convert decimal numbers to octal representation online. Free, fast, and runs entirely in your browser.
Input
Output
What Is Decimal to Octal Conversion?
Decimal to <a href="https://en.wikipedia.org/wiki/Octal" target="_blank" rel="noopener">octal</a> conversion transforms numbers from the base-10 (decimal) numeral system into the base-8 (octal) numeral system. Octal uses digits 0-7 to represent values. Each octal digit corresponds to exactly three binary bits, making it a convenient shorthand for binary in some contexts.
Octal numbers are used in Unix/Linux file permissions (e.g., chmod 755 -- see <a href="https://www.gnu.org/software/coreutils/manual/html_node/Numeric-Modes.html" target="_blank" rel="noopener">GNU Coreutils numeric modes</a>), some programming languages, and legacy computing systems. This tool converts decimal integers to their octal equivalents instantly, supporting multiple values at once.
How to Use This Tool
Enter Decimal Numbers
Type or paste one decimal number per line in the left editor. Click Sample to load examples, or Upload a text file.
View Octal Output
The right panel updates automatically with the octal representation of each decimal number. Negative numbers are prefixed with a minus sign.
Copy or Download
Click Copy to copy the octal output to your clipboard, or Download to save it as a text file.
Conversion Examples
Here are some common decimal to octal conversions:
Decimal Input
Octal Output
Frequently Asked Questions
How does decimal to octal conversion work?
Repeatedly divide the decimal number by 8 and record the remainders. The octal representation is the sequence of remainders read in reverse order. For example, 255 ÷ 8 gives remainders 7, 7, 3 — reversed: 377.
Where is octal commonly used?
Octal is most commonly used in Unix/Linux file permissions (see the chmod man page), some older programming languages, and as a compact way to represent binary data (each octal digit = 3 bits).
Is my data sent to a server?
No. All processing happens locally in your browser. No data leaves your machine.
Can it handle large numbers?
Yes. The tool uses JavaScript BigInt internally, so it can convert arbitrarily large integers without precision loss. Octal is also important in Unix file-system permissions.
Related Tools
Learn more: POSIX chmod specification, Python oct() documentation, and the MDN Number.toString documentation.