1 mg = 1000 mcgMilligrams and micrograms differ by a factor of 1000. To go from mg to mcg multiply by 1000 (decimal three places right); from mcg to mg divide by 1000.What each part meansMeaning of each symbol in the Milligrams and micrograms formulamgMilligrammcgMicrogram (1/1000 of a mg)Worked example0.25 mg = 250 mcg; 400 mcg = 0.4 mg.Practice thisOral tablets lessonWeight-based IV infusion lesson