Number Base Converter
Convert numbers between binary, octal, decimal, and hex.
- Runs in your browser
- No signup
How to use Number Base Converter
Enter a number
Type a value in binary, octal, decimal, hexadecimal or any base from 2 to 36.
See all bases
Every representation updates instantly. Flip individual bits in the 8, 16 or 32-bit view.
Convert in bulk
Use batch mode to paste many numbers, one per line, and convert them all at once.
How to convert between binary, decimal and hexadecimal
Computers store everything in binary, programmers read memory addresses and colors in hexadecimal, file permissions use octal, and people think in decimal. Number Base Converter moves between all of them, and any base from 2 to 36, instantly.
How positional bases work
In any base, each digit is worth the base raised to its position. Binary 1011 is 1x8 + 0x4 + 1x2 + 1x1 = 11 in decimal. Hexadecimal uses 0 to 9 then A to F for 10 to 15, so FF is 15x16 + 15 = 255. One hex digit maps to exactly four bits, which is why hex is a compact way to write binary.
Bits and negative numbers
The bit view shows the number as 8, 16 or 32 bits; click any bit to toggle it and watch every base update. Negative numbers are shown in two's complement, the way processors store signed integers: in 8 bits, -1 is 11111111 and -128 is 10000000.
Where you will meet these bases
Some everyday examples:
- Hexadecimal: CSS colors (#FF5733), memory addresses, MAC addresses and hashes.
- Binary: bit flags, network masks and low-level debugging.
- Octal: Unix file permissions such as chmod 755.
- Base 36: short IDs and URL shorteners, using 0 to 9 and A to Z.