Number Base Converter

Why different bases exist

Binary is how computers actually represent numbers, but it is unreadable for a person. Hexadecimal is the compromise: each digit maps exactly to four bits, so conversion is immediate and a byte fits in two characters. That is why colours, memory addresses and error codes are almost always written that way.

Why an ordinary number is not enough

JavaScript numbers lose precision beyond roughly nine quadrillion, and anyone converting to hexadecimal often deals with 64-bit values — identifiers, bit masks, truncated hashes. This tool uses arbitrary-precision integers, so the trailing digits are not silently rounded away.

Bases up to 36

Past 9 the digits run out and letters take over: base 16 uses A to F, base 36 reaches Z. There is no going further, simply because the alphabet ends. High bases are used to shorten numeric identifiers into more compact strings.

How to use it

Type the number, say which base it is written in, and the conversion appears in all bases at once, ready to copy. There is no button to press and nothing to wait for: the result settles as you type, and values stay exact even when the digits run into the dozens.

Where bases show up

Unix file permissions are written in octal, web colours in hexadecimal, bit masks and protocol flags in binary or hex, compact identifiers in high bases like 32 or 36. Computer science students meet them all in their first exercises; working developers run into them the first time a "strange" value in a log turns out to be a number written in a base other than their own.

A quick example

Take 202: in hexadecimal it becomes CA, in binary 11001010. Same value, three writings — and the tool shows them all at once, so the correspondence becomes visible instead of staying an abstract rule.