What is a gram?
A gram (g) is one thousandth of a kilogram. A paper clip weighs about a gram, and food ingredients, jewelry and medication doses are weighed in grams.
What is a kilogram?
A kilogram is metric unit of weight subdivided into 1,000 grams. The base unit of mass in the International System of Units (SI) is a kilogram and not, as is quite often mistaken, the gram.
One liter of water weighs 1kg.