Number Base Converter

Binary, octal, decimal, and hex

Computers store everything in binary (base 2), but raw binary is hard for people to read, so programmers lean on octal (base 8) and especially hexadecimal (base 16) as shorter notations for the same bits. One hex digit equals exactly four binary bits, and one octal digit equals three, which makes converting between them a matter of regrouping rather than arithmetic. Decimal (base 10) is what we use day to day. Type a value into any field above and the rest convert instantly, so you never have to do the division-and-remainder dance by hand.

Reading the bit groups

The binary output is split into 4-bit nibbles with leading zeros so the length is always a multiple of four. Each nibble corresponds to one hexadecimal digit, which makes the relationship between binary and hex obvious: 1111 1111 is two nibbles, both F, giving FF = 255. The bit count is shown too, which is handy when you care whether a value fits in 8, 16, or 32 bits — for masks, flags, colour channels, or low-level protocol fields.

Arbitrary bases from 2 to 36

Beyond the four standard bases, the custom field converts to and from any radix between 2 and 36. Bases above 10 borrow letters: base 16 uses a–f, and base 36 uses the full a–z alongside 0–9, making it the densest alphanumeric encoding and a favourite for short IDs and URL shorteners. Because conversions use BigInt, large hashes and huge decimal numbers convert exactly with no floating-point rounding. The tool handles non-negative whole numbers; copy any field with the icon beside it.