So to find out how many milligrams in grams, simply multiply it by 1000 or instead, use the converter below. 1 Gram = 1000 Milligrams. Gram is a metric system unit of mass. It is one thousandth (1/1000) of the metric system base unit, kilogram. It is a very commonly used unit of mass in daily life. The abbreviation is g. Milligram is a small unit of mass in metric system and used commonly in medicine and pharmacy etc.