vernier caliper

what is vernier caliper

A vernier caliper is indeed a measuring instrument used for accurately measuring linear dimensions, including lengths, widths, and depths. It’s particularly useful for measuring diameters of round objects as well, thanks to its measuring jaws. The jaws can be used to enclose and secure objects, enabling accurate measurements of their dimensions.

The combination of a main scale and a sliding vernier scale allows for precise readings, making it a versatile tool in various applications where accuracy is essential.

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parts of vernier caliper

vernier caliper

A vernier caliper is composed of several parts that work together to facilitate precise measurements. The main components of a vernier caliper include:

  1. Main Scale: The main scale is a graduated ruler that is fixed along the length of the caliper. It has markings in millimeters or inches, which are used to read the whole number part of a measurement.
  2. Vernier Scale: The vernier scale is a secondary scale that slides alongside the main scale. It consists of multiple divisions that are slightly shorter than the main scale divisions. The vernier scale allows for more accurate readings by indicating fractions of a main scale division.
  3. Jaws: The caliper has two pairs of jaws. The larger jaws are used to measure external dimensions (outer diameters), while the smaller jaws, often referred to as the depth rod, are used to measure depths or the internal dimensions (inner diameters) of objects.
  4. Main Scale Holder: This is the stationary part of the caliper that holds the main scale in place.
  5. Vernier Scale Holder: This is the sliding part of the caliper that holds the vernier scale. It moves along the main scale to measure various objects.
  6. Locking Screw: A locking screw or clamp is used to secure the sliding vernier scale in position once the measurement has been taken. This prevents accidental movement and ensures the accuracy of the measurement.
  7. Depth Measuring Blade: The depth measuring blade is an extension of the smaller jaws that allows for measuring depths of cavities or holes.
  8. Thumbwheel: Some modern vernier calipers include a thumbwheel that provides a fine adjustment for the position of the sliding vernier scale. This can make taking measurements more convenient.
  9. Fine Adjustment Knob: In digital vernier calipers, a fine adjustment knob is used to make precise measurements. It allows you to make small adjustments to the position of the jaws.
  10. LCD Display (Digital Calipers): Digital vernier calipers have an electronic display that shows the measurement directly in digital format. This eliminates the need for manual interpretation of scale readings.
  11. Battery Compartment (Digital Calipers): Digital calipers are powered by batteries. The battery compartment is where the batteries are placed.

These are the main parts of a vernier caliper. The combination of the main and vernier scales, along with the various jaws and locking mechanisms, allows for accurate measurements of lengths, diameters, depths, and other dimensions.

least count of vernier caliper

The least count of a vernier caliper is the smallest measurement that can be read or measured using the caliper. It’s determined by the difference in length between one main scale division and one vernier scale division. The least count allows you to make measurements more precise than the smallest main scale division.

The formula to calculate the least count of a vernier caliper is:

Least Count = Value of One Main Scale Division – Value of One Vernier Scale Division

Keep in mind that the least count varies based on the design and specifications of the vernier caliper. Vernier calipers come in different sizes and with varying scales, so the least count can be different for different calipers. Typically, the least count is engraved or indicated on the caliper itself.

vernier caliper

For example, let’s say you have a vernier caliper where one main scale division represents 1 millimeter and one vernier scale division is 0.02 millimeters. In this case, the least count would be:

Least Count = 1 mm – 0.02 mm = 0.98 mm

This means that you can read measurements on this caliper with a precision of 0.98 millimeters.

Always refer to the manufacturer’s specifications or markings on the caliper to determine its specific least count.

vernier caliper formula for least count

The vernier constant is another term for the vernier caliper’s least count. It’s the difference between one main scale division (MSD) and one vernier scale division (VSD).

Mathematically, the vernier constant (VC) is calculated as VC = 1 MSD – 1 VSD.

VC = 1 MSD – 1 VSD

The least count (LC) of a vernier caliper, when the main scale has (n-1) divisions and there are n sections on the vernier scale, is calculated as,

LC = {1 -(n-1/n) }MSD.

Therefore, The least count is calculated as 0.1 mm.

VC = Vernier constant

MSD = Main scale division

VSD = Vernier Scale Division

LC = Least count

least count formula of vernier caliper with example

formula for least count of vernier caliper, LC = {1 -(n-1)/n }MSD.

Given that the vernier scale has 10 divisions within the same space as 9 main scale divisions (n = 10) and the main scale division (MSD) is 1 millimeter, let’s calculate the least count:

LC= {1 -(10-1)/10 }


Simplifying the fraction:



LC=0.1 mm

So, according to this calculation, the least count of the vernier caliper in this example is indeed 0.1 millimeters.

What Is Zero Error?

Zero error in the context of a measuring instrument, such as a vernier caliper or micrometer, refers to a systematic deviation or offset in the instrument’s measurement reading when it is set to measure an object with a true or expected value of zero. In other words, it’s an error that occurs when the measuring instrument does not read zero when there is no actual measurement being taken.

There are two types of zero errors:

  1. Positive Zero Error: This occurs when the measuring instrument’s reading is greater than zero when the instrument’s jaws or measuring surfaces are closed and no object is being measured. It means that the instrument consistently reads a value greater than zero, which needs to be subtracted from subsequent measurements to obtain accurate results.
  2. Negative Zero Error: This occurs when the measuring instrument’s reading is less than zero when the jaws or measuring surfaces are closed and no object is being measured. It means that the instrument consistently reads a value less than zero, which needs to be added to subsequent measurements to obtain accurate results.

Zero errors can arise due to various factors, including wear and tear of the instrument, misalignment of the measuring surfaces, or manufacturing defects. It’s important to identify and account for zero errors when using any measuring instrument to ensure accurate and reliable measurements.

To correct for zero error:

  • Positive Zero Error: Subtract the magnitude of the positive zero error from any measurements taken using the instrument.
  • Negative Zero Error: Add the magnitude of the negative zero error to any measurements taken using the instrument.

Regular calibration and maintenance of measuring instruments help minimize zero errors and ensure that the instrument provides accurate measurements.

How to Read Vernier Calliper?

Reading a vernier caliper requires understanding both the main scale and the vernier scale. Here’s a step-by-step guide on how to read a vernier caliper:

  1. Understand the Scales: Familiarize yourself with the main scale and the vernier scale. The main scale is the long, graduated ruler that doesn’t move, and it has larger divisions. The vernier scale is the smaller scale that slides along the main scale, and it has finer divisions.
  2. Zero Alignment: Close the jaws of the vernier caliper so that they are gently gripping each other. Make sure the zero mark on the vernier scale aligns exactly with a main scale mark. This is the starting point for measurements.
  3. Main Scale Reading: Read the main scale value that lines up with the zero mark on the vernier scale. This value represents the whole number part of your measurement. If the zero mark is aligned with the 5 mm mark on the main scale, the main scale reading is 5 mm.
  4. Vernier Scale Reading: Look at the vernier scale and find the vernier division that lines up with a main scale division. This will be the division that coincides with a mark on the main scale. Count the number of vernier divisions to the left of this aligned division. This number represents the fraction of a division you need to add to the main scale reading.
  5. Calculating the Measurement: The total measurement is the sum of the main scale reading and the vernier scale reading. Add the whole number main scale reading to the fraction determined by the vernier scale reading.
  6. Consider the Vernier Constant: Depending on the vernier constant (also known as the least count), you might need to account for an additional fraction when taking measurements. This is the value of one vernier scale division relative to one main scale division. It might be given to you or marked on the caliper.
  7. Record the Measurement: Write down or remember the measurement you’ve obtained. Make sure to include both the main scale and vernier scale readings.

Remember that accuracy is crucial. Pay close attention to ensure you’re reading the correct divisions on both scales. Practice will help improve your ability to accurately read a vernier caliper. If you have access to a vernier caliper, it’s a good idea to practice by measuring various objects with known dimensions to build your confidence and skills.


Q. A vernier caliper has a main scale with divisions of 0.5 millimeters (MSD = 0.5 mm). The vernier scale has 25 divisions within the same space as 24 main scale divisions. Calculate the least count of the vernier caliper.


The formula to calculate the least count (LC) of a vernier caliper is:

LC=Value of one main scale division−Value of one vernier scale division

In this case, the value of one main scale division is 0.5 mm. The value of one vernier scale division can be calculated as 24/25 of the value of one main scale division (since there are 25 vernier divisions within the same space as 24 main scale divisions).

Value of one vernier scale division=24/25​×0.5mm=0.48mm

Now, plug these values into the formula to calculate the least count:

LC=0.5 mm−0.48 mm=0.02 mm

So, the least count of the vernier caliper is 0.02 millimeters.

using formula, LC = {1 -(n-1/n) }MSD.


  • Main Scale Division (MSD) = 0.5 mm
  • Vernier scale has 25 divisions within the same space as 24 main scale divisions (n = 25)

Using the formula for least count: LC = {1 -(n-1/n) }MSD.

Substitute the values:

LC = {1 -(25-1/25) } * 0.5 mm

LC = {1 -(24/25) } * 0.5 mm

LC = (1/25 ) * 0.5 mm = 0.02 mm

application of vernier caliper

Vernier calipers have a wide range of applications across various industries and fields due to their ability to provide precise measurements. Some common applications of vernier calipers include:

  1. Engineering and Manufacturing: Vernier calipers are extensively used in engineering and manufacturing industries to measure lengths, diameters, and depths of components with high precision. This is crucial for ensuring proper fits and tolerances in mechanical assemblies.
  2. Metalworking: In metalworking processes such as machining and fabrication, vernier calipers are used to measure dimensions of metal parts and components to ensure they meet design specifications.
  3. Woodworking: Woodworkers use vernier calipers to measure wood dimensions accurately, ensuring precise cuts and joinery in carpentry and cabinetry projects.
  4. Automotive: In the automotive industry, vernier calipers are used for measurements in vehicle assembly, maintenance, and repair, such as measuring brake pad thickness or engine components.
  5. Aerospace: Precision is critical in aerospace engineering, and vernier calipers are used to measure various dimensions of aerospace components, ensuring the safety and reliability of aircraft and spacecraft.
  6. Scientific Research: In scientific research, vernier calipers are used to take accurate measurements for experiments and studies, particularly in fields such as physics and materials science.
  7. Jewelry Making: Jewelers use vernier calipers to measure gemstones, settings, and other jewelry components to create pieces with precise dimensions.
  8. Quality Control: Vernier calipers play a significant role in quality control processes across industries, helping to verify that manufactured products meet specified tolerances and standards.
  9. Educational Settings: Vernier calipers are commonly used in educational settings to teach students about measurements, precision, and the use of measuring instruments.
  10. Medical and Dental Fields: While more specialized instruments are often used in medical and dental applications, vernier calipers can still be used for certain measurements, such as evaluating the dimensions of dental prosthetics.
  11. Hobbyist and DIY Projects: Vernier calipers are useful for hobbyists and do-it-yourself enthusiasts who require accurate measurements in various projects, from model building to home repairs.
  12. Archaeology and Conservation: In archaeology and artifact conservation, vernier calipers can be used to measure and document the dimensions of historical artifacts and structures.

These are just a few examples of the many applications of vernier calipers. Their ability to provide precise measurements makes them an essential tool in fields where accuracy is paramount.

advantages of vernier caliper

Vernier calipers offer several advantages due to their precision and versatility in measuring various dimensions. Here are some of the key advantages of using a vernier caliper:

  1. High Precision: Vernier calipers can provide measurements with a high level of accuracy, typically down to a fraction of a millimeter or inch. This precision is essential in applications where exact measurements are crucial.
  2. Versatility: Vernier calipers can measure lengths, depths, and diameters of various objects, making them versatile tools across different industries and fields.
  3. Ease of Use: While using a vernier caliper requires understanding the scales and how to read them, once the technique is mastered, the tool is relatively easy to use, making it suitable for both professionals and students.
  4. Non-Destructive Measurement: Vernier calipers allow for non-destructive measurements, meaning you can measure an object’s dimensions without altering or damaging it.
  5. Cost-Effective: Compared to more complex measuring instruments like micrometers, vernier calipers are relatively affordable while still providing a high level of accuracy.
  6. Visual Confirmation: The scales on a vernier caliper provide a visual representation of the measurement, allowing users to confirm the measurement visually, which can be helpful for quality control and quick assessments.
  7. Measuring Different Objects: Vernier calipers can measure both external dimensions (using the larger jaws) and internal dimensions (using the smaller jaws), making them suitable for a wide range of objects.
  8. Portable: Vernier calipers are compact and lightweight, making them easy to carry and use in various settings, including fieldwork and workshops.
  9. Quick Measurements: Once the user becomes familiar with the tool, measurements can be taken relatively quickly, making them efficient for tasks that require multiple measurements.
  10. Educational Value: Vernier calipers are often used in educational settings to teach students about precision measurement techniques, helping them develop skills that can be valuable in various technical fields.
  11. Reliability: When properly maintained and calibrated, vernier calipers can provide consistent and reliable measurements over time.
  12. Limited Skill Requirement: While mastering more advanced measuring instruments might require specialized training, vernier calipers can be learned relatively quickly by individuals with basic measurement skills.

Despite these advantages, it’s important to note that the accuracy of vernier calipers can be affected by factors such as user technique, wear and tear, and the precision of the instrument itself. Regular calibration and proper usage are essential to ensure accurate measurements.

disadvantages of vernier caliper

While vernier calipers offer several advantages, they also have some limitations and potential disadvantages:

  1. Limited Resolution: Vernier calipers provide high precision, but their resolution is limited by the smallest division on the vernier scale. This can be a drawback when measuring very small dimensions or when higher precision is required.
  2. Readability Challenges: Reading the scales on a vernier caliper accurately can be challenging, especially for individuals with limited eyesight or those who are not familiar with the instrument. This can lead to measurement errors.
  3. Human Error: Incorrect alignment of the scales or misinterpretation of readings due to parallax (the apparent shift of the scale when viewed from an angle) can lead to measurement inaccuracies.
  4. Time-Consuming: While quick measurements are possible with practice, taking accurate measurements with a vernier caliper can be time-consuming compared to digital measuring devices like micrometers or digital calipers.
  5. Limited Range: Vernier calipers have a limited measurement range compared to some other instruments, such as external micrometers or specialized tools for measuring larger dimensions.
  6. Complexity for Beginners: Learning to read a vernier scale correctly can be challenging for beginners, and it might require some time and practice to become proficient.
  7. Subject to Wear and Tear: Over time, the sliding parts of the caliper can experience wear and tear, affecting the accuracy of measurements. Regular maintenance and calibration are necessary to mitigate this issue.
  8. Subject to Environmental Factors: Vernier calipers can be sensitive to changes in temperature and humidity, which might affect the accuracy of measurements if not accounted for.
  9. Limited Digital Readout: Traditional vernier calipers lack a digital readout, which means that there’s no automatic recording of measurements. This can be a drawback in situations where data logging is important.
  10. Measuring Fragile Objects: When measuring delicate or fragile objects, the pressure applied by the measuring jaws might cause damage or deformation.
  11. Not Suitable for High-Volume Measurements: For applications requiring a high volume of measurements, manual reading and recording can be time-consuming and less efficient compared to digital alternatives.
  12. Internal Measurements Limited: While vernier calipers can measure internal dimensions using the smaller jaws, their design and limitations might make them less suitable for very small or deep internal measurements.

Despite these disadvantages, vernier calipers remain valuable tools in many industries and educational settings. They are especially useful when high precision is required but the cost and complexity of more advanced measuring instruments are not justified.

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