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.
What is a microgram?
A microgram is a unit of mass in the metric system that is equal to one millionth of a gram. It is commonly used to measure very small amounts of substances, such as medications, vitamins, or pollutants. The symbol for microgram is μg. To put it into perspective, a single grain of table salt typically weighs around 58,500 micrograms.