15 grams of gelatin powder is 0.529 oz (15 g) in weight. When poured into a loose pile, it is 2.34 in (5.94 cm) wide and 0.982 in (2.49 cm) tall, which is about the size of a cherry tomato.

In kitchen measures
1.56 tablespoons
4.68 tsp · 1.56 tbsp · 0.098 cups
about the size of a cherry tomato
Gelatin powder typically ranges 0.6–0.7 g/mL depending on how it's packed. A firmly packed scoop weighs more.