One teaspoon of onion powder is a small amount that measures 0.333 tbsp (4.93 mL) in volume. When poured into a loose pile, it is 1.4 in (3.55 cm) wide and 0.587 in (1.49 cm) tall, which is about half the size of a cherry.

In kitchen measures
1 teaspoons
1 tsp · 0.333 tbsp · 0.021 cups
about half the size of a cherry
Onion powder typically ranges 0.4–0.5 g/mL depending on how it's packed. A firmly packed scoop weighs more.