How to Convert Decimal to Binary, Hex and Octal

Computers store everything in binary (base 2), so any decimal number eventually becomes a string of 1s and 0s. The classic by-hand method is repeated division: divide your decimal number by 2, write down the remainder (0 or 1), then divide the quotient by 2 again, and keep going until you reach 0. Read the remainders from bottom to top and you have the binary value. For example, 255 becomes 11111111, and 10 becomes 1010.

The Number Base Converter does this for you instantly. Pick Decimal as the input base, type your number, and the Binary row shows the result. Because the tool also displays octal and hexadecimal, you can see how the same value looks across bases without running three separate conversions.

Hexadecimal (base 16) uses the digits 0-9 plus A-F, where A is 10 and F is 15. It is compact, which is why colors, memory addresses and byte values are usually written in hex. Octal (base 8) uses digits 0-7 and still shows up in things like Unix file permissions.

With Tooldrop you do not choose an output base at all. Enter your number once and every base is shown together, so 255 in decimal lines up as 11111111 in binary, 377 in octal and FF in hex side by side. That makes it easy to copy whichever representation you need, or to sanity-check a value you already have.

The conversion happens entirely on your device. When you type a value, your browser parses it and computes the other bases locally, so the number never leaves your machine and nothing is uploaded to a server. That is good for privacy and it also means the tool responds instantly, even offline once the page has loaded.

Like the rest of Tooldrop, the Number Base Converter is free to use with no sign-up and no limits on how many conversions you run. It handles whole numbers (integers) across binary, octal, decimal and hexadecimal.