Capsule Volume Calculator

A capsule is a cylinder capped at each end with a hemisphere, the smooth, rounded shape of a medicine capsule, a propane or LPG tank, an air receiver, a pressure vessel or many liquid storage tanks. Because it is one of the most common shapes used for tanks and vessels, working out its volume and surface area is a genuinely practical task, and this calculator does both from just two measurements: the radius of the tube and the length of the straight cylindrical section between the two domed ends. Enter those and it returns the total volume, the surface area, and the overall length end to end, all updating instantly as you adjust the inputs. The volume is the figure most people are after, because it gives the capacity of the tank or vessel, and it is found with a neat piece of reasoning: the two hemispherical ends together make exactly one full sphere, so the capsule volume is simply the cylinder plus a sphere of the same radius. The surface area is what you need for coating, insulating, painting or estimating heat loss across the whole vessel, and it likewise splits into the curved side of the cylinder plus a full sphere for the two ends. Getting these by hand means combining cylinder and sphere formulas and keeping the radius consistent through cubes and squares, which is fiddly and easy to slip on, so the calculator keeps it fast and accurate. It is a useful tool for engineers and designers sizing vessels, for anyone estimating tank capacity, and for students learning to build composite solids from simpler shapes. The exact formulas and a worked example follow below.

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