The volume of a rectangular-shaped object can be determined using an instrument called the "Vernier caliper." The product of length, breadth and height of a rectangular-shaped object gives its volume. For determining the length, breadth and height of the object with maximum accuracy, a Vernier caliper is used.
There are two sets of jaws in the Vernier caliper, which measure the internal and external dimensions of any object. The object can be rectangular or cylindrical. According to Britannica, there is a graduated fixed scale and a movable Vernier scale in the instrument. The fixed scale provides the basic reading for the measured distance, and the Vernier scale provides the precise fractional reading.