I am trying to calculate the dia. of a pipe 60 inches long that will hold a gallon of water. What is the formula?


Hi Landry,

First you need to know which gallon. A US gallon is 231 cubic inches and a British imperial gallon is 277.42 cubic inches.

The volume of a cylinder is

r 2 L where r is the radius and L is the length. Your cylinder is 60 inches long so 60 r 2 = 231 or 60 r 2 = 277.42 Hence if the gallons are US gallons or if the gallons are British imperial gallons.

The diameter is twice the radius.

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