A 40 g pile of whey protein powder is wider but significantly shorter than 300 mL of water held in a glass. You can visualize the water as a cylinder 2.8 in (7.11 cm) wide and 3.5 in (8.89 cm) tall, while the powder forms a mound 3.67 in (9.32 cm) wide and 1.54 in (3.91 cm) tall.

Biggest vs smallest
1.05× the size
40 g of whey protein powder vs 300 mL of water
Typical adult or standard sizes; real ones vary.