What is octal used for?

Octal (base 8) groups three binary bits into one digit using 0-7. It is best known from Unix file permissions, where modes like 755 are octal representations of read, write, and execute bits.

What is the largest number I can convert?

Up to 9,007,199,254,740,991, the largest integer JavaScript can represent exactly. Larger values are rejected to avoid silent precision loss.

Does this upload my number?

No. The conversion runs entirely in your browser — nothing is sent to any server.

Decimal to Octal Converter

Convert any whole number to octal (base 8) instantly.

Decimal to octal — base-10 to base-8

Enter a whole number and this tool returns its octal (base 8) value, plus the binary and hexadecimal forms. Octal is handy for Unix file permissions and other bit-grouped values.

The conversion runs entirely in your browser — nothing is uploaded.