Use a measured water cylinder, drop in the object, the amount of water displaced represents the volume of the object
Partition (or divide) the irregular object into summation of regular objects and then calculate the volume.
To calculate the volume of an irregular object you will need a container with meaurements and water. Place the irregular object in your container and fill with water until the entire object is covered. Record volume A. Then remove the irregular object and record volume B. The volume of your irregulare object is equal to volume A minus volume B.
You take the mass of the object and divide it by the volume.
[object Object]
You cannot calculate the volume of an object using only the density; you must also calculate the mass.You can calculate the mass by simply weighing the object.Density = Mass / VolumeTherefore Volume = Mass/Density.If you cannot be bothered to calculate the mass, simply measure the object. Multiply the length, times the width, times the height and you have the volume.
Density is the ratio of mass to volume. Thus, the density of an object is the mass of the object divided by its volume.
The volume of a solid object such as a rock or pebble can be determined by submerging it in a liquid in a graduated cylinder or other container. The difference in the volume of the liquid is the volume of the object.
Mass divided by volume
conclusion
The usual approach is to divide the object's mass by its volume.
Volume = Length * Width * Height.
Volume = Length x width x height.