0.5 cups of rolled oats is a serving that weighs 1.67 oz (47.3 g). When poured into a loose pile, it is 3.94 in (10 cm) wide and 1.77 in (4.51 cm) tall, which is about the size of a tennis ball.
Nobody has photographed 0.5 cups of rolled oats yet.
Volume
Weighs 1.67 oz (47.3 g)
about the size of a tennis ball
Rolled oats typically ranges 0.38–0.48 g/mL depending on how it's packed. A firmly packed scoop weighs more.