Number Base Converter

A number base, or radix, is how many digits a way of writing numbers uses. Decimal has ten, 0 to 9. Binary has two, the ones and zeros a computer stores. Hexadecimal has sixteen, 0 to 9 and A to F, so that each digit stands for exactly four bits and a byte is always two digits.

The value does not change with the base, only the way it is written: 255, FF, 11111111 and 377 are one and the same number.

• Type into any field: decimal, hexadecimal, binary, octal, or a base of your choice from 2 to 36. The other fields follow as you type.
• Prefixes are read where they belong, 0x in the hexadecimal field, 0b in binary and 0o in octal. Spaces and underscores between digits are ignored, so 1010 1010 and FF_FF work.
• Below the fields: the number of bits, the bytes in both byte orders, the Unicode character the number stands for, and how its bits read as an 8, 16, 32 or 64-bit value, signed and unsigned.
• Numbers of any size stay exact. A click on a value selects all of it, and the address bar follows the field you type in.

• Only whole numbers are converted. A fraction such as 0.1 has no exact binary form, and a converter that pretends otherwise rounds without saying so.
• In C and some older tools a leading zero means octal, so 0755 there is 493. The decimal field reads 0755 as 755; write it in the octal field, or as 0o755.
• A negative number keeps its minus sign in every base. The two's complement a computer stores it as is shown under Fixed widths.
• Hexadecimal and the larger bases are written in capitals. Lower case is read just as well.