Binary to Decimal Converter

How to convert binary to decimal

1. Type or paste a binary number (only 0s and 1s). Spaces, underscores and a 0b prefix are allowed.
2. The decimal value appears at the top, with hexadecimal and octal below it.

Doing it by hand

Each binary digit is worth a power of two, doubling from right to left: 1, 2, 4, 8, 16, 32, 64, 128… Write those values above the digits and add the ones under a 1. For 101101: 32 + 0 + 8 + 4 + 0 + 1 = 45. A faster method for long numbers is "double and add": start at 0, and for each digit from the left, double the total and add the digit. 1 → 2+0 = 2 → 4+1 = 5 → 10+1 = 11 → 22+0 = 22 → 44+1 = 45.

Eight bits make a byte, which holds 0 to 255. Negative numbers in computers usually use two's complement, where the leftmost bit means negative; type a minus sign here to convert a signed value directly. The converter uses exact big-integer arithmetic, so 64-bit and longer numbers are converted without rounding.