Base Converter

Base Converter

Convert very large integers between binary, octal, decimal, hexadecimal, and any custom base from 2 to 36.

A Base Converter changes a whole number between the counting systems computers and programmers use every day. Humans count in decimal, base ten, but computers store everything in binary, base two, and programmers shorten long binary values with octal, base eight, and especially hexadecimal, base sixteen, where the digits run to the letter F. Colours on web pages, memory addresses, network settings, and error codes are all written in these bases, so converting quickly and correctly is a daily need for students and developers.

This tool goes further than a basic converter in two ways. First, it accepts any custom base from 2 to 36, using letters for digit values above nine, which is helpful for coursework and encoding exercises. Second, it uses arbitrary-precision arithmetic, so very long values convert exactly instead of being rounded by the normal limits of a calculator. Every common base is shown together in the result, and invalid digits for the chosen base are reported clearly, for example if you try to use the digit 8 while converting from octal.

How to use

  1. Type the value exactly as it appears in its original base, without spaces or prefixes.
  2. Set the From base to match that value, such as 16 for a hexadecimal colour or code.
  3. Read all of the converted results together in the box below, including your chosen base.
  4. Copy the line you need into your code, assignment, or notes.
  5. If an error appears, check for digits that cannot exist in the starting base.

Frequently asked questions

Why do programmers use hexadecimal so much?

One hexadecimal digit represents exactly four binary digits, so long machine values become short and readable while staying easy to convert back. Memory addresses, colour codes like FF5733, and file signatures are written in hex for that reason. Decimal has no such neat relationship with binary, so conversion is slower to do by eye.

What does base 36 mean?

Base 36 uses all ten digits plus all twenty-six letters, giving 36 symbols in total. It produces very short codes for large numbers, which is why link shorteners and licence systems sometimes use it. This tool supports every base from 2 to 36, so you can experiment with any of them.

Can the tool handle negative numbers?

Yes. A leading minus sign is preserved through the conversion and shown in every result base. Be aware that computers internally store negatives in a special form called two's complement, which looks different from a simple minus sign, but for general conversion the signed result here is the clear mathematical answer.

Are very large numbers exact?

Yes. The tool uses big-integer arithmetic in your browser, so a fifty-digit decimal number or a long hexadecimal string converts digit for digit without rounding. Standard calculators silently lose precision beyond about sixteen digits, which is exactly the problem this approach avoids.