Convert from firkin [butter, soap] to grano, grani [Italy]

Unit Definition (firkin [butter, soap])
The firkin [butter, soap] is a traditional unit of weight for butter and soap, equal to 4 stone or 56 pounds (about 25.40 kilograms).

Unit Definition (grano, grani [Italy])
The grano, grani [Italy] is a traditional Italian weight unit, varying in size but typically about 50 milligrams. The plural is grani.