Decimal to Octal Converter

Octal is base 8, a number system that uses only the digits 0 through 7. Each position is worth eight times the one to its right. Decimal is base 10 and uses digits 0 through 9.

The most common place is Unix and Linux file permissions, where modes like 755 or 644 are octal. Octal also shows up in older computing, some hardware registers and as a compact way to group binary three bits at a time.

Repeatedly divide the decimal number by 8 and record each remainder. Reading the remainders from last to first gives the octal value. For example 64 divided by 8 is 8 remainder 0, then 8 divided by 8 is 1 remainder 0, so 64 becomes 100.

No practical limit. The converter uses arbitrary-precision integers, so even very large numbers convert to the exact octal value with no rounding.

Yes. Commas and spaces are stripped before converting, so grouped input like 1,000 or 4 096 works the same as the plain number.

No. The conversion happens entirely in your browser, so the numbers you enter never leave your device.