Mass, according to the University of Memphis, is the amount of matter in a given sample, while volume is the physical size of the sample. Mass and volume are two of the most important physical characteristics of matter when it comes to physics, and are used for measuring density.
Mass is measured in kilograms or pounds and is colloquially referred to as weight. Mass and weight aren't the same quantity; mass is fixed, whereas weight depends on gravity. Volume is measured in cubic meters, or the units are scaled to make the numbers more easily readable unless scientific notation is used.
Density is the amount of matter in a given volume, expressed as a ratio of kilograms per cubic meter.
In gases, volume and density vary inversely because gases expand to fill their entire container, whereas liquids simply take the shape of their container.
Volume is calculated by taking the physical measurements of an object. For example, the formula for volume of a cylinder is pi multiplied by the square of the radius (the formula for area), multiplied by the height of the cylinder, according to Annenberg Learning. To find the volume of a complexly shaped object, it's best to add the volumes of simpler component shapes.