Somewhere between "learn to code" tutorials and actual programming sits the rite of passage of writing numbers in binary — and it starts with plain decimal-to-binary conversion. The method is repeated division by 2: divide the number, write down each remainder, and read the remainders bottom-to-top. For 200, the remainders spell out 11001000. This converter frames the answer around the bit widths that matter in real computing: type a number into the Decimal Number box and the 8-bit and 16-bit readouts show where it lands (200 fits in 8 bits, whose max is 255; 70,000 needs more than 16 bits, whose max is 65,535), while the Hex equivalent box gives the programmer's shorthand. IP addresses, subnet masks, file permissions, and microcontroller registers are all binary wearing decimal costumes, so this translation is genuinely useful, not just homework. Once you can see that 255 is eight 1s and 256 needs a ninth bit, the whole binary world clicks into place.

With the pre-filled defaults — Decimal Number 255 — the Decimal to Binary returns 8-bit binary max (255) 255, 16-bit max (65535) 255, Hex equivalent 255. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.