How do I convert a number to octal?

Type the number in the input box, choose its base from the dropdown (decimal, binary, octal or hexadecimal), and all four representations update instantly, including the octal value.

Does it support negative numbers?

Yes. Prefix the number with a minus sign and the converter handles negative integers in every base.

What happens if I type an invalid digit for the chosen base?

The tool checks the input against the selected base — for example binary only accepts 0 and 1 — and shows a clear error message until you fix the input.

Is it free and private?

Yes, it is free, needs no signup, and everything runs in your browser.

Octal Number Converter

Convert integers between decimal, binary, octal and hexadecimal. Type a number, pick its base, and see all four values update live.

Number

Input base

Decimal

—

Binary

—

Octal

—

Hexadecimal

—

Digits allowed per base: binary 0–1, octal 0–7, decimal 0–9, hexadecimal 0–9 and A–F. A leading minus sign makes the number negative.

How to use

Type any whole number in the input box.
Choose the base the number is written in from the dropdown.
Read the converted decimal, binary, octal and hexadecimal values instantly.

What is octal?

Octal is a base-8 number system that uses only the digits 0 to 7. It was widely used in computing because each octal digit maps exactly to three binary bits, which made it handy for reading machine-level values.

Octal Number Converter

How to use

What is octal?

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