Dial caliper: Definition, Least Count, Drawing, Parts, How to use

Dial caliper: Definition, Least Count, Drawing, Parts, How to use

What is a Dial Caliper?

Dial Caliper is a measuring Instrument that is used for Linear measurements with high Accuracy, to check the quality of the product 

What is the Dial Caliper least Count?

The least count of the dialCaliper is 0.02 mm if we consider the following specifications 

For example, let’s consider a dial caliper with the following specifications:

  • Main scale graduation: 1 mm
  • Number of divisions on the dial scale: 50

The least count would be calculated as follows:

Least Count= Smallest Division on Main Scale/Number of Divisions on Dial Scale

Least Count= Number of Divisions on Dial Scale / Smallest Division on Main Scale

Least Count =1 mm/50 =0.02 mm

Dial Caliper Drawing

Dial Caliper drawing with parts
Dial Caliper drawing with parts

What are Dial caliper parts?

A dialcaliper consists of several parts that work together to facilitate precise measurements. Here are the main components of a typical dial caliper:


Inside Jaws (or Faces): 

These are the two arms on the inside of the caliper used to measure the internal dimensions of an object.

Outside Jaws (or Faces): 

These are the two arms on the outside of the caliper used to measure the external dimensions of an object.

Main Scale:

The main scale is typically located on the fixed portion of the caliper and provides the primary measurement reading. It is graduated in millimeters (mm) or inches.

Dial or Vernier Scale:

The dial or vernier scale is a circular or semi-circular scale usually located on the front of the caliper. It allows for more precise readings by providing additional subdivisions beyond the main scale. The user reads the measurement by aligning the dial pointer with the corresponding graduation on the dial or vernier scale.

Dial or Pointer:

The dial or pointer is the hand that moves around the dial or vernier scale. It points to the measurement on the dial scale and indicates the additional measurement beyond the main scale.


The slider is the movable portion of the caliper that houses the jaws. It can be adjusted to measure different objects by sliding along the main scale.

Locking Screw:

Some dial calipers have a locking screw that allows the user to secure the jaws in place once the measurement has been taken. This helps maintain the measurement while the caliper is removed from the object being measured.

Depth Measuring Rod:

Many dial calipers come with a depth measuring rod, an extension on the bottom of the caliper that can be used to measure the depth of holes or recesses.

How to use Dial Caliper?

Using a dial caliper involves a series of steps to accurately measure dimensions. Here’s a general guide on how to use a dial caliper:

Step 1 

Familiarize Yourself with the Parts:

Understand the different parts of the dial caliper, including the main scale, dial or vernier scale, jaws (inside and outside), slider, locking screw (if present), and depth measuring rod (if applicable).

Step 2 

Zero Calibration:

Before making measurements, ensure the dial or pointer is aligned with the zero on the dial or vernier scale. If it’s not at zero, use the small adjustment wheel (if available) to zero it.

Step 3 

Select the Measurement Mode:

Decide whether you need to measure external dimensions (using the outside jaws), internal dimensions (using the inside jaws), or depth (using the depth measuring rod).

Step 4 

Position the Caliper:

Open the jaws by sliding the slider along the main scale. Place the object to be measured between the jaws. For internal measurements, ensure the inside jaws make contact with the surfaces to be measured.

Step 5 

Close the Jaws:

Gently close the jaws around the object, making sure they make secure contact without excessive force.

Step 6 

Read the Main Scale:

Read the measurement value directly from the main scale where the zero on the dial aligns. This is the main part of the measurement.

Step 7

Read the Dial or Vernier Scale:

Note the value indicated by the pointer on the dial or vernier scale. This provides additional precision beyond the main scale.

Step 8

Calculate the Total Measurement:

Add the values from the main scale and the dial or vernier scale to get the total measurement. The formula is:

Total Measurement=Main Scale Reading+Dial or Vernier Scale Reading

Total Measurement=Main Scale Reading+Dial or Vernier Scale Reading

Step 9

Record the Measurement:

Note down the measurement value, including the unit of measurement (millimeters or inches).

Locking (Optional):

If your dial caliper has a locking screw, you can use it to secure the jaws in place before removing the caliper from the object. This helps maintain the measurement.

Check and Confirm:

Double-check your measurement to ensure accuracy. If needed, repeat the measurement for verification.

By following these steps, you can effectively use a dial caliper to measure various dimensions with precision. Remember to handle the caliper with care to maintain its accuracy over time.

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