Number Base Converter
Type a number in any base and instantly see its equivalent in binary, octal, decimal, and hexadecimal, side by side — using exact BigInt math so even very large numbers convert correctly.
Developer Tools Runs entirely in your browser
The conversion happens entirely inside your browser.
Binary101010
Octal52
Decimal42
Hex2A
What this tool does
Converts numbers between binary, octal, decimal and hexadecimal, showing the value in every base at once.
When to use it
- Reading a hexadecimal value in code or a log and wanting it in decimal.
- Working with bit masks or flags in low-level programming.
- Converting a colour value or a memory address.
- Learning how the same number is represented in different bases.
How to use it
- Type the number into the "Value" field.
- Choose the "Current base" of what you entered.
- Read the equivalent value in the other bases.
A practical example
Input
The value FF in hexadecimal.
Output
255 in decimal, 11111111 in binary and 377 in octal.
Limitations
- A value containing characters invalid for the chosen base is rejected with a clear message — a 9 in octal, for instance.
- Four bases are supported: binary, octal, decimal and hexadecimal.
- Very large numbers can exceed the browser's numeric precision.
- Fractional values are not supported; the conversion is for whole numbers.
Privacy and processing
The conversion happens entirely inside your browser.
Technical notes
- Character validity is checked before conversion, so an invalid input cannot produce a wrong-looking answer.