One simple way of measuring the volume of a container is to fill it with liquid and then pour the volume into a measuring vessel, such as a graduated cylinder. If you don’t have such a device, however, you may be able to calculate the volume of a container if it has a simple shape for which the volume formula is commonly known.
Measure the height, H, and circumference, C, of a cylindrical container to calculate the volume as HC/(4*pi), where pi is 3.14159, after rounding. Pi is the ratio of circumference to diameter--a constant for all circles.
Measure the circumference, C, of a spherical container to calculate the volume as C^3/(6*pi^2). Here, ^3 means "cubed" and ^2 means “squared.”
Find the volume of a truncated cone, narrower at the bottom than the top by first measuring the circumference at the bottom, c, and top, C. Measure the height, H. Calculate the radii at the top and bottom: c/(2_pi) and C/(2_pi). Denote them r for the bottom circumference and R for the top. Solve for the volume with the equation pi_H_(R^2 + r^2 + R_r)/3. Note that if the walls are vertical, then R=r, the container is a cylinder and you get the formula for a cylinder: pi_H*R^2.