What is the formula to figure the volume of a cylinder? We have a cylinder that is 2 3/4" in inside diameter and a gallon of oil that needs to fill it. We are trying to figure out how long the cylinder should be. Can you help us?

Thank you,
Kelly Wichmann

Are you sure you want a gallon? A gallon is 231 cubic inches. The volume of a cylinder is pi*r²*h and if d = 2.75, then to get the height of the cylinder you divide 231 by pi*r² which is about 231 over 3.14159*(2.75/2)². I get height = 38.8917 (which is more than 3 feet high!).