How to use the Number Base Converter
- Type a number.
- Choose the base it’s written in.
- Read it in binary, octal, decimal, hex and any other base.
About this tool
Computers store everything in binary (base 2). Hexadecimal (base 16) is a compact way to write binary — each hex digit is exactly 4 bits — so it appears in colour codes, memory addresses and MAC addresses. Octal (base 8) is still used for Unix file permissions like 755.
The converter uses JavaScript BigInt, so even 100-digit numbers convert exactly with no rounding. Prefixes such as 0x, 0b and 0o are accepted, and spaces or underscores between digits are ignored.
Frequently asked questions
How do I convert decimal to binary?
Type the number with “Decimal” selected and read the Binary row. 255 is 1111 1111.
What is 0xFF in decimal?
255. Choose Hexadecimal as the input base and type FF (the 0x prefix is optional).
Does it support fractions or negative numbers?
Negative whole numbers, yes (shown with a minus sign). Fractions and two’s-complement representations aren’t supported.