What is Vernier Calliper? Principle, types and Using Method

What is Vernier Calliper?

A vernier caliper is a type of precision measuring instrument that is frequently used in engineering, science, and industrial settings to measure an object’s dimensions with extreme accuracy. A screw or thumbwheel can be used to adjust the caliper’s two parallel jaws, one of which is fixed and the other movable, so that it will accommodate objects of various sizes.

A Vernier scale, a secondary scale that moves along the caliper’s main scale, is attached to the movable jaw of the instrument. The Vernier scale offers additional, finer gradations that are superimposed on the primary scale, enabling the user to take exact measurements. The user can accurately determine the fractional portion of the measurement by reading the Vernier scale.

Vernier calipers come in a variety of styles and sizes, including digital and analog models, and can be used to gauge depth, step values, and internal and external dimensions. They are frequently employed in manufacturing, machining, engineering, scientific, and educational settings to teach students about precision measurement.


Who invented the vernier caliper?

French mathematician and instrument maker Pierre Vernier created the Vernier caliper in 1631. An instrument for measuring linear dimensions like length, diameter, and thickness is the Vernier caliper. It has two jaws, one of which is fixed and the other mobile, as well as a graduated scale that can measure in both metric and imperial units. By displaying the portion of graduation on the main scale that the movable jaw has reached, the Vernier scale enables more accurate measurements to be taken.


Working principle of vernier caliper

Vernier calipers are a type of measuring instrument used to precisely determine an object’s internal and external dimensions. The vernier caliper operates on the principle of using two scales—a main scale and a sliding vernier scale—to achieve extremely precise measurements.

The vernier scale, which is used to measure the finer details of an object’s dimensions, is a sliding scale with slightly different graduations from the main scale, which is a ruler with fixed graduations.

The main scale is first used to calculate the total number of millimeters, centimeters, or inches of the object being measured when using a vernier caliper. The fractional parts of the measurement are then calculated using the vernier scale, which has a higher level of accuracy than the main scale.

The main scale and vernier scale are parallel, and the reading is taken where the lines of the two scales meet. The fractional portion of the measurement is determined by the number of graduations on the vernier scale that line up with the primary scale.

The vernier caliper’s operating principle is based on the observation that the distance between graduations on the vernier scale is marginally smaller than that of the main scale. By using the sliding vernier scale to line up with the graduations on the main scale, the measurement can be taken with extreme accuracy due to the difference in distance. 


Least count of vernier caliper and screw gauge 

The smallest value that can be measured using a measuring device is represented by its least count.

A vernier caliper typically has a minimum count of 0.02 mm or 0.001 inches. This indicates that the device has a measurement accuracy of 0.02 mm or 0.001 inches.

Depending on the instrument, a screw gauge, also referred to as a micrometer, may have a different least count. The least count, however, for the majority of common screw gauges, is 0.01 mm or 0.001 inches. This indicates that the device has a measurement accuracy of 0.01 mm or 0.001 inches.


Types of Vernier calipers

Vernier calipers come in two different categories:

Manual Vernier Calliper: To measure the dimensions of an object, this type of Vernier caliper has a main scale and a Vernier scale that is manually adjusted. While the Vernier scale has smaller graduations that enable more precise measurements, the main scale is typically marked in millimeters or inches.

Digital Vernier Calliper: The measurement readings are displayed on a digital display on this type of Vernier caliper. It functions by electrically transforming the linear displacement of the Vernier scale into a signal that is then shown on the screen. Vernier calipers that are digital instead of manual are typically more accurate and simpler to read.

Difference between Manual and Digital Vernier Caliper

Feature Manual Vernier Calipers Digital Vernier Calipers
Measuring range Typically up to 300 mm/12 inches Typically up to 300 mm/12 inches
Measuring accuracy Can be as accurate as 0.02 mm/0.001 inch Can be as accurate as 0.01 mm/0.0005 inch
Reading measurements Requires reading scale and Vernier scale The digital display shows measurements directly
Ease of use Can be tricky for beginners to read accurately Easy to read and use, even for beginners
Battery requirement Not required Requires batteries for the digital display
Cost Generally less expensive than digital models Generally more expensive than manual models
Durability Generally more durable due to mechanical design Sensitive electronics may be more prone to damage
Additional features None Some models may have additional features, such as data output or absolute/relative measurement modes



How to use a vernier caliper?

  1. Before using the caliper, make sure it is clean and free of debris.
  2. Sliding the upper jaw toward the fixed lower jaw will close the caliper’s jaws.
  3. Confirm that when the jaws are closed, the scale is zeroed out or reads zero. If not, calibrate the scale using the zero adjustment screw.
  4. Decide on the measurement unit you’ll be using—millimeters or inches—and set it on the caliper’s scale.
  5. Set the item you want to measure between the caliper’s jaws. Make sure the item is flush with the jaws.
  6. Squeeze the jaws of the caliper together lightly until they are tightly affixed to the thing being measured.
  7. Check the main scale measurement where the sliding vernier scale’s zero mark is located.
  8. Locate the measurement on the vernier scale that exactly matches a mark on the primary scale. The vernier scale reading is as follows.
  9. To get the total measurement, add the readings from the main scale and the vernier scale.
  10. If the vernier scale’s zero mark is not parallel to a main scale mark, locate the nearest parallel vernier mark and write down the decimal point that it corresponds to.
  11. To get the final measurement, add this decimal point to the main scale reading.
  12. To measure a hole’s depth, attach the depth gauge to the end of the caliper and insert it into the opening. The depth gauge will reach all the way to the bottom of the hole, giving a precise reading.
  13. To measure an object’s thickness, place it between the caliper’s jaws and make sure the jaws are tightly clamped around the object.
  14. To determine an object’s outside diameter, wrap the caliper’s jaws around it and make sure they are firmly in place.
  15. To determine an object’s internal diameter, insert the caliper’s jaws into the object and make sure they are snug against it.


To get precise measurements when using a vernier caliper.

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