Enter a value in stone (st) in the "From" field, and the equivalent value in dram (apothecary) (dr ap) will be displayed in the "To" field automatically.

The conversion factor between stone and dram (apothecary) is calculated automatically based on their relationship to the base unit in the mass / weight category.

Yes, you can convert between any units in the mass / weight category. Use the dropdown menus to select different units.