About the Number Base Converter
This tool converts a decimal number into its binary, octal, and hexadecimal equivalents at once. Enter a number such as 255 and instantly see it as 11111111 in binary, 377 in octal, and FF in hexadecimal. These four bases are the ones that matter most in computing.
What number bases are
A number base is how many distinct digits a system uses before it rolls over to a new place. Decimal, base ten, uses digits 0 to 9, the system we count in daily. Binary, base two, uses only 0 and 1. Octal, base eight, uses 0 to 7. Hexadecimal, base sixteen, uses 0 to 9 and then A to F to represent values ten through fifteen. The same quantity can be written in any base; only the representation changes, not the value.
Why computers use binary and hexadecimal
Computers work in binary because their circuits have two stable states, on and off, which map naturally to 1 and 0. But long strings of binary are hard for people to read, so hexadecimal is used as a compact shorthand: each hex digit represents exactly four binary digits, so a byte fits in just two hex characters. This is why colours in web design, memory addresses, and many low-level values are written in hex. Octal sees less use today but still appears, notably in file permissions on Unix systems.
How conversion works
Converting from decimal to another base repeatedly divides the number by the base and records the remainders, which read in reverse give the result. Converting back multiplies each digit by its place value, which is a power of the base. The tool does this for all three target bases simultaneously, so you can see how one value looks across the systems programmers use most.
Common uses
Programmers convert bases constantly when working with colours, bitmasks, memory, character codes, and file permissions. Students learning computer science use base conversion to understand how data is represented. Anyone debugging low-level data, reading a hex dump, or setting a colour code will find quick conversion essential.
Tips and related tools
Enter a positive whole number for clean results; very large numbers stay accurate up to the limits of standard number precision. Hexadecimal output uses uppercase A to F by convention. For converting hex colour codes specifically to RGB, the HEX to RGB Converter is purpose-built, and for Roman numerals the Roman Numeral Converter. All conversion happens in your browser.
Frequently Asked Questions
What bases are supported?
Binary (2), octal (8), decimal (10), and hexadecimal (16).
What input does it take?
A decimal number, converted to the other bases.
Does it handle large numbers?
Up to JavaScript’s safe integer limit.
Are negatives supported?
Enter positive whole numbers for clean results.
Where does the conversion run?
Entirely in your browser. Your data is never uploaded to a server.