1000 mg. According to the formula that mass equals volume times density, 1000g equals 1kg equals 1000000mg, which can be calculated. The milliliter is a unit of volume used to measure the volume of liquid. In daily life, milliliter is often used to measure the volume of liquids such as medicines, drinks and cosmetics. ML can also be used in scientific experiments and medical fields, such as measuring the dose of chemical reagents and drugs.