Number base converter

How to convert between number bases

Type a number and choose its base. It appears in binary, octal, decimal and hex at the same time, and in a custom base from 2 to 36 if you set one. The math uses BigInt, so 256-bit hashes and other large numbers convert exactly with no floating-point rounding. For example, ff in base 16 is 255 in decimal and 11111111 in binary.

Made for low-level work

Decode a hex color, inspect a bitmask or turn a permission value from octal into binary. A custom base field covers unusual bases like base 3 or base 32.

Forgiving input

Prefixes like 0x, 0b and 0o are accepted and removed for you. Digits that aren't valid in the chosen base get a clear error, so typos are easy to fix.

Common conversions

Hex color channels such as ff convert to 255. File permission 755 in octal is 111101101 in binary, which reads as rwxr-xr-x. The decimal 1024 is 400 in hex and 10000000000 in binary. Base 36 uses the digits 0 to 9 and the letters a to z, which is why it is popular for short IDs.

Before you start

Base Converter works on the text or values you enter. Output: All bases. The settings appear before anything runs, so you can check them first. Your original file is never changed.

The value you enter is processed in your browser. Still test the output where it will be used. Clean formatting does not prove the data is safe or correct.

Keep the original until you have opened and checked the result. The work happens in this browser tab, so the size you can handle depends on your device's memory, your browser and the file itself.

How to use the number base converter

1. Type a number and select its base.
2. Read the binary, octal, decimal and hex results.
3. Set a custom base from 2 to 36 for anything else.
4. Copy the version you need.