Classicly

Measure Sugar and Fruit: Use the same standard measuring cup, holding ½ pint, level full, for both sugar and fruit. If sugar is weighed, weigh fruit also. To measure fruit for jam, pack solidly into cup until juice and fruit come to top. If there is a slight shortage, fill last cup, or fraction of cup, with water. If not quite enough juice for jelly, mix water with pulp in jelly bag and squeeze again.