Number Base Converter

Convert between binary, octal, decimal and hex

Computers count in more than one language. People use decimal (base 10), but processors and memory work in binary (base 2), while programmers often lean on hexadecimal (base 16) and octal (base 8) as shorter ways to write long binary strings. This Number Base Converter turns a whole number written in any one of those bases into all four at once, updating the moment you type.

What each base means

A base is simply how many distinct digits a number system uses. Binary uses two digits (0 and 1), octal uses eight (0–7), decimal uses ten (0–9), and hexadecimal uses sixteen (0–9 then A–F, where A=10 and F=15). One hex digit maps neatly onto four binary digits, which is why hex is so popular for colors, memory addresses and byte values. Everything runs in your browser — nothing you type is ever uploaded.

How to use it

1. Pick the base of the number you already have from the Input base menu.
2. Type your whole number into the Value box.
3. Read the binary, octal, decimal and hexadecimal results below as they update live.
4. If the box turns up an error, check that every digit is valid for the base you chose.
5. Switch the input base at any time to convert a different value — the fields refresh instantly.

FAQ

Does it handle very large numbers?

Yes. It uses BigInt arithmetic, so there is no 32- or 64-bit ceiling — convert numbers hundreds of digits long with exact results.

Are hex letters case-sensitive?

No. You can enter hexadecimal digits in upper or lower case (a–f or A–F). Results are shown in uppercase for readability.

Can I convert decimals or fractions?

This tool converts whole integers only. Negative numbers are supported with a leading minus sign, but fractional parts are not.

Why does it reject my number?

Each base only allows certain digits — a "2" is invalid in binary and a "G" is invalid in hex. The error line tells you which characters are allowed for the selected base.