1 cup of rolled oats is about the size of a coffee mug. When poured into a loose pile, it measures 4.97 in wide and 2.24 in tall.

In kitchen measures
16 tablespoons
48 tsp · 16 tbsp · 1 cups
about the size of a coffee mug
Rolled oats typically ranges 0.38–0.48 g/mL depending on how it's packed. A firmly packed scoop weighs more.