If you're wondering how to calculate the volume of a rectangular tank (also known as cuboid, box, or rectangular hexahedron), look no further! You may know this tank as a rectangular tank – but that is not its proper name, as a rectangle is a 2D shape, so it doesn't have a volume. where f f f is the height of the filled portion. The volume of a rectangular prism is the space it occupies in the three-dimensional plane. It is measured in cubic units such as m 3, cm 3, mm 3, ft 3. Formula The formula to calculate the volume of a rectangular prism is given below: About the Topic The Volume is the amount of space an object takes up. You can find the rectangular prism with V = BH and use the V= length × width × height. Both formulas are helpful to find the rectangular prism. The formula volume equals the area of the base by multiplying with the height. Online volume of rectangle calculation. Use this simple geometry volume of rectangle calculator to calculate volume.