One cup of regular, cooked long-grain white rice has 205 calories. This number represents 10 percent of a person's daily caloric intake, based on a 2,000-calorie diet.
Pre-cooked or instant long-grain white rice has 193 calories per cup. Both short-grain and medium-grain white rice have 241 calories per cup. Long-grain white rice has less fiber and is enriched with vitamins and minerals. It cooks up fluffy and separate. Medium-grain and short-grain rice contain more amylopectin, but short-grain releases more starch and is stickier when cooked.
Amylopectin is a molecule released from a grain of rice as it cooks. The higher the amount of amylopectin, the starchier the rice. Amylose is another rice starch and causes some rice varieties to become less starchy when cooked.