Question: what is the difference between iu and mcg?
Answer: What's the difference between a milligram (mg), microgram (mcg), and an International Unit (IU)? In the metric system, 1000 milligrams (mg) is a unit of mass equal to 1 gram and 1000 micrograms (mcg) is equal to 1 milligram (mg). ... 1 IU is the biological equivalent of 0.025 mcg cholecalciferol or ergocalciferol.