Vernier calipers are used to measure the distance between objects. They are used to measure the dimensions of an object. They can measure both internal and external dimensions accurately. They are used to measure exact linear measurements in various fields. The vernier is a subsidiary scale replacing a single measured-value pointer, and has for instance ten divisions equal in distance to nine divisions on the main scale. The interpolated reading is obtained by observing which of the vernier scale graduations is coincident with a graduation on the main scale, which is easier to perceive than visual estimation between two points.