100 grams of long-grain rice is a common measurement for a single portion. You can picture this amount as being about the size of a tennis ball.

In kitchen measures
7.96 tablespoons
23.9 tsp · 7.96 tbsp · 0.497 cups
about the size of a tennis ball
Long-grain rice typically ranges 0.75–0.92 g/mL depending on how it's packed. A firmly packed scoop weighs more.