That depends a great deal on the type and size of tub as well as on how deep you fill it. Most people are not going to fill the tub up as much for small children as they will for an adult and a really big and fat person cannot put as much water into the tub as a short, skinny person (unless they want the tub to overflow).
Typical bathtubs used in the USA can hold 40 to 60 gallons of water - but if you fill them to the top you will overflow the water when you get in.
300 gallons
Depends on the bathtub.
A standard bathtub can hold an average of 40-60 gallons of water, which is equivalent to about 160-240 cups of water.
30 gallons
Depends on the size of the tub. Not all tubs are the same size.
gallons
QF = V / t = 80 gal / 16/3 min = 15 GPM<-----------------------------
You would measure the water in a bath tub in gallons.
Gallons
75 gallons. Typical bathtub dimensions 5ft x 2 ft x 1 ft (waterline) = 10 cubic ft = ~75 gallons or 284 liters
about 100-150 gallonsAnother opinion75 - 80 gallons Your bathtub may be bigger than mine. So, measure length times width times depth of the water and multply by 7.5 to get the amount of gallons in your tub... or any other vessel.
The most reasonable unit of capacity for a bathtub is typically measured in gallons or liters. This measurement helps determine the amount of water the bathtub can hold when filled to the desired level.