A common guideline: 1/2 cup uncooked rice per person for a side dish, and 3/4–1 cup uncooked per person if rice is the main part of the meal. Uncooked rice roughly triples when cooked (varies by type).
Adjust for appetites and whether other sides are served. For meal prep, 2 cups uncooked rice yields about 6 cups cooked—enough for several servings.