How to Use a Caliper: A Complete and Detailed Guide

How to Use a Caliper: A Complete and Detailed Guide

If you need to take the most accurate measurements, then it is crucial to know exactly how to use a caliper. Calipers are a brilliant device when you require to take accurate measurements, especially for small objects.

What Is a Vernier Caliper?

The Vernier caliper is a scale which was invented in 1631 by the French mathematician, Pierre Vernier. It is a measuring device which can precisely measure linear dimensions. It is highly useful when you have to measure the diameter of circular objects as its measuring jaws can be secured on both the sides of the circumference.

The scale is graduated either in tenths of an inch or in millimeters. Additionally, they typically show metric or imperial measurements, but there are some that can measure in both.

The range (or also referred to as its maximum capacity) of the Vernier caliper is the difference between the smallest and the largest value which it is capable of measuring. This is exactly equal to the main scale’s length.

A majority of the Vernier calipers have a maximum capacity of six inches, which is 300mm. That being said, you will also find calipers on the market which either has a larger or smaller maximum capacity.

How to Use a Caliper

A good quality caliper is capable of offering accurate measurements to within +/- 0.001-inch, which comes up to 0.02 mm. This is precise enough and has a reading error of 0.05 mm which is 1/20mm to ensure that you are not cutting too deep when milling and that the design will fit inside the piece of material which you are using.

All this is only achievable when you know how to use the caliper properly. Here is a guide which will demonstrate how to take various types of measurements.

General Steps

  1. Before you begin to measure, ensure that you are closing the jaws as lightly as you can.
  2. If you’re going to measure an object which has a round cross-section, then you have to ensure that the axis of this object to the caliper is perpendicular. This is extremely important and even necessary as you need to measure the full diameter, not just the chord.
  3. Typically, you don’t have to pay much attention (unless required to) to the top part of the scale as it is calibrated in inches. You have to use the bottom part of the scale which is usually in metric units.
  4. You will also notice that there is a sliding scale and a fixed scale. The boldface numbers present on the fixed scale are in centimeters, whereas the tick marks that are on the fixed scale which are in between these boldface numbers are millimeters.
  5. On the sliding scale, you will find 10 tick marks altogether. The tick mark on the left-most side of the sliding scale allows you to read the fixed scale. This is the number of the whole millimeters which the jaws of the caliper are open.

Putting It to Use

Let’s try this out with your Vernier caliper.

  1. Slide the caliper between two and four inches. On the sliding scale, you will find that the left-most tick mark will be between 21 millimeters and 22 millimeters. This means that 21 is the number of whole millimeters.
  2. From there, you have to find the tenths of the millimeters. You will notice on the sliding scale that there are 10 tick marks. These are of the same width as the nine tick marks which are present on the fixed scale.
  3. What this basically means that at most, at least one of these tick marks present on the sliding scale will be aligned with the fixed scale’s tick mark. All of the other tick marks will be missed.

Understanding the Tick Marks

On the sliding scale, the number of the tick mark which is aligned will be able to tell you the number of the tenths of the millimeters. So, on the sliding scale, the very third tick mark is in coincidence with the one that is above it. That means the caliper should read at (21.30 ± 0.05) millimeters.

If there are two tick marks which are adjacent on the sliding scale and they look aligned equally as their counterparts on the fixed scale; it means that the reading will be halfway between these two tick marks. Hence, if on the sliding scale, the third and the fourth tick mark appear to be aligned equally, then the reading on the caliper would be at (21.35 ± 0.05) millimeters.

In some rare occasions when the reading appears to be a clean number such as two centimeters, then you must not forget to include zero decimal places. This will show the reading error along with the precision of the measurement. This means that it will not be two centimeters, but it will rather be (20.00 ± 0.05) millimeters or (2.000 ± 0.005) centimeters.

What Are the Advantages and Disadvantages of a Vernier Caliper?

Now that you have a fair understanding of how to use a Vernier caliper, it is also vital that you know its advantages and disadvantages which will keep you well aware of it when you use it.


  • Accuracy: Vernier caliper will surely provide you with precise and accurate measurements.
  • Integrated scales: Since the Vernier scale and the main scale are built into the tool, you do not require another instrument for measurements such as a tape or a ruler.
  • Durability: A majority of Vernier calipers is made from high-quality stainless steel. Steel is highly durable, and with proper care, it will last for decades.


  • Needs good eyesight: It is a given that Vernier calipers are not the easiest to read considering how small the measurements are printed. This means that you could misread.
  • Learning the instrument: A Vernier caliper is a unique instrument for measurements. This means that the user has the learn how to use and read before they start taking measurements.
  • Errors: If you use the instrument to take measurements continuously, it can possibly lead to errors in reading as you require a lot of concentration.


Knowing how to use a caliper is important to take the most accurate and precise measurements. We are certain that with our guide and with some practice, you will be able to measure everything without hassles!

Click here to add a comment

Leave a comment: