A diagram of vernier calipers, a device used to measure the distance between two opposite sides of an object, showing the individual parts:
Diagram: Joaquim Alves Gaspar, modified by ed g2s
- Outside large jaws: used to measure external diameter or width of an object
- Inside small jaws: used to measure internal diameter of an object
- Depth probe: used to measure depths of an object or a hole
- Main scale in centimeters, marked every millimeter
- Main scale in inches, marked every 1/16 of an inch
- Vernier scale gives interpolated measurements to 1/20 of a millimeter
- Vernier scale gives interpolated measurements to 1/128 of an inch
- Retainer: used to block movable part to allow the easy transferring of a measurement
Here the metric scale shows a distance of 2.475 cm between the jaw faces: the 0 mark on the vernier is between 2.4 and 2.5, and the 7.5 mark is the one best aligned with a mark on the main scale. Similarly, the inch scale shows (155/8)/16, or 125/128, of an inch.