100 g to mg

100 g = 100,000 mg

Multiply the gram value by 1,000, because milli- means one thousandth: 100 g × 1,000 = 100,000 mg.

Divide by 1,000: 100,000 mg ÷ 1,000 = 100 g. That inverse step is the standard way to check a dosage or a nutrition label quoted in milligrams.

One milligram is 1,000 micrograms, so 100 g = 100,000,000 mcg = 100,000 mg. Reading mg as mcg is a thousandfold error, which is why prescriptions spell the prefix out.