Number Base Converter

A number base (or radix) is the count of distinct digits a positional numeral system uses. Everyday numbers are decimal (base 10), while computers store everything in binary (base 2). Hexadecimal (base 16) and octal (base 8) are compact ways to write binary: each hex digit is exactly four bits (a nibble) and each octal digit is three bits, which is why memory addresses, colour codes and byte dumps are written in hex and Unix file permissions in octal.

This converter updates every base as you type in any field. It uses JavaScript BigInt arithmetic, so there is no 53-bit precision limit — you can convert 128-bit hashes, 256-bit keys or numbers with hundreds of digits exactly. Prefixes such as 0x, 0b and 0o are recognised in any field, spaces and underscores are ignored, and negative numbers are supported. The custom base field covers every radix from 2 to 36 using the digits 0–9 followed by the letters A–Z.

Computers represent negative integers with two's complement: invert all bits of the positive value and add one. The table shows the bit pattern a value would have in 8, 16, 32 and 64-bit signed integers (int8 to int64), which is useful when reading memory dumps, debugging overflow bugs or working with bitwise operations.

The text section encodes any text, including emoji and non-Latin scripts, into its UTF-8 bytes and decodes hex, binary or decimal bytes back into text — handy as a quick hex encoder/decoder. Everything runs locally in your browser; nothing is uploaded.

Related tools: hex colour codes such as #FF8800 are three hex bytes, which the color converter turns into RGB and HSL. For binary data in text form, use the Base64 encoder. Octal file modes like 755 are explained by the chmod calculator, and binary subnet masks by the subnet calculator.