A mL of most water-based liquids is about a gram. However, it's more complicated than that, because liquid cough medicines are not pure "medicine" ... they're mostly water and sugar. You'd need to read the box to see how many mg of actual "medicine" there is in a mL of the syrup.
It is 15,000 milligrams.
1 mg equals how many grams?
A grain is a unit of measurement in medicine. A one half grain equals 30 mgs as part of the apothecaries system
1000 mg equals 1 gm
1000 mcg equals 1 mg.
1000 mcg equals 1 mg.
8200 mg
45.5ng=mg
a gram equals a thousand milligrams, so 3,000 mg
544,000,000 mg
250,000 mg
15400 mg