How many kilograms are in 5000 grams? The definition of a kilogram is one thousand grams. You have five thousand grams. You want to know how many kilograms you have. If you divide five thousand by one thousand, what do you get? Five.

There are 1000 (one thousand) milligrams in one gram. "Milli" is sometimes used to describe something that has one thousand of it, like a Millenium has one thousand years.