12 g to mg

12 g = 12,000 mg

Multiply the gram value by 1,000, because milli- means one thousandth: 12 g × 1,000 = 12,000 mg.

Divide by 1,000: 12,000 mg ÷ 1,000 = 12 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 12 g = 12,000,000 mcg = 12,000 mg. Reading mg as mcg is a thousandfold error, which is why prescriptions spell the prefix out.