Binary to Decimal Converter
Type a binary number and see it in decimal straight away, along with its hex and octal forms. It works the other way too: type a decimal number to get its binary.
How to convert binary to decimal
- 1Type the binary number in the Binary box.
- 2Read the decimal value below it.
- 3Copy it, or type in the Decimal box to go the other way.
Doing it by hand
Each binary digit is worth twice the one to its right: 1, 2, 4, 8, 16 and so on. Add up the values where there's a 1. For 101010 that's 32 + 8 + 2 = 42.
Any size, any base
Numbers of any length convert exactly, with no rounding, and negative numbers work too. Binary, octal, decimal and hexadecimal each get a box, and another box takes any base from 2 to 36.
Long binary
Turn on “Group digits” to split binary into groups of four, which makes long values far easier to check.
Frequently asked questions
- Is my data uploaded?
- No. The conversion runs in your browser and nothing is sent anywhere.
- What is 1111 in decimal?
- 15: 8 + 4 + 2 + 1.
- What is 11111111 in decimal?
- 255, the largest value one byte can hold.