Vernier Caliper: Least Count, Parts, How to read, FAQ’s [PDF]

What is Vernier Caliper?

The Vernier Caliper accurately measures dimensions of a specimen, including diameter (outer and inner), length, depth, etc., earning it the name “Precision Measuring Instrument

Parts of Vernier Caliper

A Vernier Caliper consists of several essential parts:

  • Outside jaws: These are designed to measure the external dimensions of objects. By placing the object between the outside jaws, you can accurately determine its outer diameter or width.
  • Inside jaws: These jaws are specifically used for measuring the internal dimensions of objects. By inserting the inside jaws into a cavity or hole, you can obtain precise measurements of its inner diameter.
  • Measuring depth probe: This is used to measure the depth of objects. The depth or length of a groove could be included. The depth probe extends from the main body of the caliper and allows you to measure the distance from the reference surface to the bottom of the object.
  • Main scale (cm): The main scale on the Vernier Caliper provides measurements in centimeters. It is a graduated ruler that allows you to read the whole numbers and decimal fractions of centimeters.
  • Main scale (inch): Similar to the main scale in centimeters, this scale provides measurements in inches. It enables you to read whole inches and fractions of inches.
  • Vernier scale (cm): The Vernier scale is an auxiliary scale that allows for more precise measurements. It is divided into smaller increments than the main scale, enabling you to measure with greater accuracy.
  • Vernier scale (inch): Just like the Vernier scale in centimeters, the inch Vernier scale provides finer divisions for precise measurements in inches.
  • Retainer: The retainer is a component that secures the movable part of the Vernier Caliper in place, preventing it from moving when measurements are not being taken. This ensures stability and accuracy during the measurement process.

Each of these parts plays a crucial role in the functioning of the Vernier Caliper, allowing for precise and versatile measurements of various dimensions.

vernier caliper diagram

Working Principle of Vernier Caliper

Calipers primarily consist of two jaws, namely the Upper Jaw and the Lower Jaw, which are used to secure the component being measured. The Upper Jaw is used to measure the inner diameter of the specimen. The Lower Jaw is employed to measure its outer diameter.

There are two scales incorporated in calipers: the Main Scale and the Vernier Scale. Both of these scales provide measurements in both inches and millimeters, offering flexibility in unit selection.

To ensure accurate measurements, a locking screw is utilized to secure the jaws at the desired position, maintaining stability during the measurement process.

How to Read Vernier Caliper?

  • The main scale is located along the length of the ruler and is used to slide the jaws open and closed.
  • The Vernier scale is located on the bottom jaw and moves along the main scale during measurement.
  • The main scale measures in millimeters or tenths of an inch.
  • Each mark on the main scale represents one millimeter. The marks on the Vernier scale represent one-tenth of a millimeter.
  • To read the main scale, look at the zero mark on the Vernier scale, which indicates the measurement on the main scale.
  • If the Vernier scale zero doesn’t align perfectly with a main scale marking, use the rest of the Vernier scale to find the most accurate alignment with a main scale marking.
  • Smaller measurement options on the Vernier scale may have additional markings, such as .02 millimeters, for even more precise readings.
vernier caliper diagram
Main scale and Vernier scale of Vernier Caliper

Vernier Caliper Formula

Measurement = M.S.R + (V.S.R*L.C)

Least Count of Vernier Caliper

Least Count (L.C) = 1 MSD – 1 VSD

Main Scale Division Calculation

If the zeroth division of the Vernier scale aligns with a specific number (let’s assume it’s 10) on the Main scale, then the Main scale reading (MSR) is 10mm.

M.S.R = 10mm

Vernier Scale Division Calculation

Next, examine the figure to identify the division on the Vernier scale that aligns precisely with the Main scale.

In the given figure, the 10th division on the Vernier scale coincides exactly with a division on the Main scale. Counting from 0 to 10, there are 5 divisions on the Vernier scale.

Up to the 10th division, there are 50 divisions. Therefore, the Vernier Scale division is 50.

V.S.R = 50.

Calculation of Least Count of Vernier Caliper

We know that,

Least Count =  1 MSD – 1 VSD

1 VSD= (49/50) MSD= 0.98 MSD

Substituting the above value in the formula, we get

Least Count (L.C) =1 MSD – 0.98 MSD= 0.02 mm

Therefore, Least Count is 0.02 mm

Measurement = M.S.R + (V.S.R*L.C) = 10+ (50*0.02) = 10+1 = 11mm

Video on How to use Vernier Caliper

Dial Caliper and Vernier Caliper Difference

difference between vernier caliper and dial caliper

Applications of Vernier Caliper

  • Educational Sector: Vernier calipers are commonly used in educational settings to teach and practice precision measurement techniques.
  • Steel Industries: Vernier calipers are utilized in steel industries for measuring dimensions of various steel components accurately.
  • Science Labs: Vernier calipers find extensive use in science laboratories for conducting experiments and measurements in physics, engineering, and other scientific disciplines.
  • Aerospace Industries: Vernier calipers are employed in the aerospace industry to measure critical dimensions of components used in aircraft and spacecraft manufacturing.
  • Medical Purposes: Vernier calipers can be used in medical fields for measuring anatomical features, surgical instruments, and other medical devices.

Advantages of Vernier Caliper

  • Accuracy and Precision: Vernier calipers provide precise and accurate measurements over a wide range of dimensions.
  • Versatility: They can measure various dimensions of components, including outer diameter, inner diameter, depth, and length.
  • Durability: Vernier calipers made from stainless steel, which is an anti-corrosive material, offer high durability and longevity.
  • Cost: Vernier calipers are relatively affordable compared to other types of calipers available in the market.
  • Elimination of Rulers or Measuring Tapes: Vernier calipers provide superior accuracy compared to traditional rulers or measuring tapes.

Disadvantages of Vernier Caliper

  • Possibility of Errors: Reading measurements on a Vernier caliper requires concentration and precision, as any mistakes can lead to errors in measurement.
  • Alternative Accurate Tools: If one is unable to use Vernier calipers effectively, other accurate tools such as dial calipers can be used as alternatives.
  • Magnifying Glass or Eyesight: A good magnifying glass is sometimes necessary, especially if one’s eyesight is not optimal, to ensure accurate readings and prevent errors.


What is the least count of vernier caliper

If you have read the entire article then you would have probably understood what is least count of vernier caliper. Here is a quick revision to the same. The least count of a Vernier caliper is the smallest measurement that can be read or recorded using the instrument.
The formula to calculate the least count of a Vernier caliper is:

Least Count = Value of one main scale division / Total number of Vernier scale divisions

The value of one main scale division depends on the scale used and can be obtained from the scale markings. The total number of Vernier scale divisions can also be determined by counting the divisions on the Vernier scale.

Example: The value of one main scale division is 1 mm and there are 10 divisions on the Vernier scale, the least count would be:

Least Count = 1 mm / 10 divisions = 0.1 mm
Therefore, the least count of this Vernier caliper would be 0.1 mm.

How to read vernier caliper?

Following are the steps to read vernier caliper:

→ Identify the main scale reading by noting the measurement at the zero mark on the Vernier scale.
→ Determine the Vernier scale division by finding the division that aligns with the main scale.
→ Divide the 1 main scale division by the total vernier scale divisions.
→ Multiply the Vernier scale division value by the number of divisions the Vernier scale aligned with on the main scale.
→ Add the whole number and fractional parts to obtain the final measurement reading.

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