It's about 55 times as big as a Basketball
In other words, 100 gallons is 53.284013264 times the size of a Basketball, and the size of a Basketball is 0.01876735514 times that amount.(NBA official ball standards, Size 7)
A NBA official ball, manufactured by Spalding, is a Size 7 ball and measures about 1.87673551360 gallons. The surface of these balls have 4,118 pebbles with a diameter of 2.5 mm each.
It's about 70 times as big as a Bowling Ball
In other words, 100 gallons is 71.838388317 times the size of a Bowling Ball, and the size of a Bowling Ball is 0.01392013412 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 1.39201341150 gallons. 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 80 times as big as The Blood in a Human Body
In other words, 100 gallons is 80 times the size of The Blood in a Human Body, and the size of The Blood in a Human Body is 0.0 times that amount.(for 70 kg body; average altitude; average)
The volume of blood in the average human body is about 1 gallons. Persons living at high altitude, however, may have up to an additional 0.50 gallons of blood to compensate for the lower oxygen level.
It's about 200 times as big as a Human Stomach
It's about 250 times as big as an Ostrich Egg
In other words, 100 gallons is 231.9 times the size of an Ostrich Egg, and the size of an Ostrich Egg is 0.00431 times that amount.(Struthio camelus) (for common ostrich; average)
The largest egg produced by living birds, ostrich eggs measure about 0.42270 gallons in volume. The eggs take about nine weeks to hatch, with males and females taking turns incubating them.
It's about 650 times as big as a STARBUCKS Venti Coffee
In other words, 100 gallons is 640 times the size of a STARBUCKS Venti Coffee, and the size of a STARBUCKS Venti Coffee is 0.002 times that amount.A STARBUCKS Venti coffee drink measures 0.160 gallons. The name of the size, Venti, is the Italian word for twenty.
It's about 800 times as big as a Blood Donation
In other words, 100 gallons is 800 times the size of a Blood Donation, and the size of a Blood Donation is 0.00 times that amount.(American Red Cross donation volume)
The typical donation amount when giving blood is about 0.10 gallons. Donated quantities of blood typically have a viable shelf life of about 42 days.