Binary to Decimal Converter – Free, Online, Private

Bits to an integer

The input is a base-2 integer. 101010 is 42, because it is 32+8+2. Spaces are removed so 1010 1010 is the same as 10101010. A prefix 0b is not accepted; delete it. A sign is not accepted on this page; invert the bits yourself if you are looking at two's complement. The conversion uses BigInt, so a 256-bit mask does not collapse to a float the way Number would above 2^53. The output is the base-10 digits with no separators and no 0d prefix. An empty box and a box of only spaces are errors. A single 0 is the number zero.

What people paste by mistake

Hex digits such as A are rejected, which stops a hex dump from being read as binary and producing a confident wrong number. Decimal digits 2 through 9 are rejected for the same reason. A string of bits with a trailing h or b fails until you delete the suffix. Signed bytes are a different question: 11111111 as an unsigned integer is 255, and as an 8-bit two's complement value it is -1. This page prints 255. The width is not in the text, so the page will not guess. The decimal to hex page is the neighbor when you want 0xFF instead of 255.

Worked example

101010 is 42. 11111111 is 255. 100000000 is 256. A 1 followed by sixty-four zeros is 2^64, which still prints exactly, not as 18446744073709552000 with a rounded tail. That exactness is the reason to use BigInt rather than the number base tool's smaller examples, though the full number base converter on Utilo covers octal and arbitrary bases too. This page is the direct binary question.

Checked locally

Bit strings from a capture or a flag field are not interesting to an attacker by themselves, and they are still processed only in the tab. There is no upload. Pair the result with the hex page when a protocol document mixes both radices.

Frequently asked questions