Text to hex converter

Type text on the left for hex on the right, two digits a byte. Swap the boxes to go back.

Decoding is forgiving about formatting. It ignores spaces and commas and strips any 0x prefixes, so you can paste from a hex dump, a debugger or a stack overflow answer without cleaning it up first. Separator changes what sits between bytes on the way out.

One byte holds a number from 0 to 255, which takes three digits in decimal and eight in binary. In base 16 it always takes exactly two, so a row of bytes lines up into neat columns and you can read a dump without counting.

The four bits behind each hex digit have their own name. A nibble, half a byte. That joke has been in the literature since the 1950s and nobody has managed to kill it.

Hex uses A to F, so a handful of English words can be written as numbers. Programmers have been doing it for decades: 0xDEADBEEF marks freed memory in some systems, and 0xCAFEBABE is the first four bytes of every compiled Java class file, chosen by James Gosling's team before Java was even called Java.

It is a good habit to know about. A file that begins 0xCAFEBABE or 0x89504E47 is telling you what it is before you open it, which is how the cipher identifier recognises formats too.

Hex, binary and Base64 all write the same bytes at different densities: two characters a byte, eight, and about 1.33.

For the number behind a character rather than its bytes, see character codes and Unicode code points.