For a classic plov where rice is cooked alongside equal proportions of meat and vegetables, a standard serving is about 80 to 100 grams of dry rice per person.
For four people, you will want between 320 and 400 grams of dry rice in total. In volume measurements, one standard US cup of uncooked long-grain rice weighs roughly 185 to 200 grams, which means you will need approximately 1.75 to 2 cups of dry rice. If you are serving hearty eaters or want a small amount left over for second helpings, you can comfortably increase that to 450 to 500 grams, or about 2.25 to 2.5 cups.
A helpful principle when planning plov is following the traditional balanced ratio: match your dry rice weight with equal weights of meat and carrots. For example, using 400 grams of dry rice, 400 grams of meat, and 400 grams of carrots will yield four satisfying, complete portions without unnecessary waste.