The Ca hardness is usually measured in milligrams per liter (mg/L) or parts per million (ppm). The factor 50.045 is used to convert from the molar mass of calcium to the calcium hardness.
Calculation of Magnesium Concentration:
Mg²⁺ (in mg/L) = (Mg hardness) / (24.305)
Mg hardness is measured in mg/L or ppm. The factor 24.305 is used to convert from the molar mass of magnesium to the magnesium hardness.