It's about as big as a Human Stomach.
It's about three-fifths as big as The Blood in a Human Body.
In other words, the size of The Blood in a Human Body is 2 times 12 cups.(for 70 kg body; average altitude; average)
It's about one-and-three-fourths times as big as an Ostrich Egg.
In other words, the size of an Ostrich Egg is 0.5747 times 12 cups.(Struthio camelus) (for common ostrich; average)
The largest egg produced by living birds, ostrich eggs measure about 6.763 cups in volume. The eggs take about nine weeks to hatch, with males and females taking turns incubating them.
It's about half as big as a Bowling Ball.
In other words, 12 cups is 0.53878791238 times the size of a Bowling Ball, and the size of a Bowling Ball is 1.856017882 times that amount.(USBC specifications; tenpin)
According to United States Bowling Congress specifications, a tenpin bowling ball should measure at least 10.795 cm (4.25 in) in radius for a total volume of about 22.272214585 cups. Because regulation balls measure the same diameter irrespective of their weight, ball density varies by size and balls weighing less than about 5 kg (11 lbs) will float in water.
It's about two-fifths as big as a Basketball.
In other words, 12 cups is 0.39963009948 times the size of a Basketball, and the size of a Basketball is 2.5023140181 times that amount.(NBA official ball standards, Size 7)
It's about one-third as big as a Bowling Ball (packed).
In other words, 12 cups is 0.34482426392 times the size of a Bowling Ball (packed), and the size of a Bowling Ball (packed) is 2.9000279407 times that amount.(64% packing density) (USBC specifications; tenpin)
It's about one-fourth as big as a Basketball (packed).
In other words, 12 cups is 0.25576326366 times the size of a Basketball (packed), and the size of a Basketball (packed) is 3.9098656535 times that amount.(64% packing density) (NBA official ball standards, Size 7)
A NBA official ball, manufactured by Spalding, is a Size 7 ball measures about 30.027768218 cups. These balls have 4,118 pebbles each with a diameter of 2.5 mm