Magnesium sulfate, or anhydrous magnesium sulfate and magnesium sulfate heptahydrate, is a magnesium-containing compound with the molecular formula MgSO4 (or MgSO4·7H2O). Anhydrous magnesium sulfate is a commonly used chemical reagent and drying agent. However, magnesium sulfate typically refers to magnesium sulfate heptahydrate, as it is less soluble, easier to weigh than anhydrous magnesium sulfate, and more convenient for quantitative control in industrial applications.