64 fluid ounces of water is a volume equivalent to about the size of a half-gallon. It is easy to picture as 8 cups of water that fill a glass 5.17 in (13.1 cm) wide.

In kitchen measures
8 cups
384 tsp · 128 tbsp · 8 cups
about the size of a half-gallon
Water typically ranges 1–1 g/mL depending on how it's packed. A firmly packed scoop weighs more.