For example, say you have 75 grams. Simply multiply 75 by 1,000, which equals 75,000. So, 75 grams (g) is equal to 75,000 milligrams (mg). [3] X Research source

For instance, if you have 500,000 milligrams, divide 500,000 by 1,000, which equals 500. Therefore, 500,000 milligrams (mg) is equal to 500 grams (g). [7] X Research source