In the measurement and inspection category of our machine education lessons, we’ve dedicated this article to vernier caliper reading lesson notes. How to read a caliper. For those who want to learn how to read 1/10, 1/20, and 1/50 calipers, we’ll provide simple, easy explanations. We hope you’ll enjoy the explanations, supported by exercises and caliper questions.
Caliper Reading
A caliper is a measuring tool with precise graduated markings. While caliper precision varies by preference, the most commonly used precisions are 1/10 (0.1 mm), 1/20 (0.05 mm), and 1/50 (0.02 mm). Caliper reading may seem difficult to some, but it’s actually quite easy once you grasp how it works.
How is a caliper read?
A caliper has two basic parts: a moving jaw and a fixed jaw. The first step in reading a caliper is finding which graduation on the fixed scale the zero point of the moving scale (the vernier) lines up with. Let’s take a closer look at the example above:
First step in caliper reading. Reading the whole-number value
We can see that the zero point on the moving jaw’s scale falls somewhere between 34 and 35 on the fixed scale. So what’s the measured value? Is it 34.6? 34.8? What’s the value after the decimal point?
Second step in caliper reading. Finding the caliper’s precision
Many calipers have their precision printed on them. For example, the precision of the caliper shown above is 1/20 = 0.05 mm. Even if the precision isn’t printed on the caliper, it’s still possible to determine it. We’ll explain how to find a caliper’s precision further below.
Third step in caliper reading. Finding the coinciding line
In this step, we determine where a line on the moving jaw’s scale exactly lines up with a line on the fixed jaw’s scale. (In the example above, this is where the number 7 is.)
Since the caliper’s precision — the spacing between two lines — is 0.05, the coinciding point gives us: 14 x 0.05 = 70, which is the digit after the decimal point.
The final step in caliper reading. Now that we’ve found the digit after the decimal point, the value read on the caliper is 34.70 mm.
How is a caliper’s precision determined?
A caliper’s precision is the smallest measurement increment it can measure.
How to determine a caliper’s precision is shown above.
1/10 calipers have a precision of 0.1 mm. In other words, this type of caliper can take measurements like 6.2, 7.3.
1/20 calipers have a precision of 0.05 mm. In other words, this type of caliper can take measurements like 6.25, 7.35.
1/50 calipers have a precision of 0.02 mm. In other words, this type of caliper can take measurements like 6.22, 7.34.
Question: Which of the following caliper types is more precise?
a) 1/10 b) 1/20 c) 1/50
Answer: The 1/50 caliper is the most precise. It can measure increments as small as 2% of a millimeter (0.02).
Reading a 1/10 Caliper
How do we know a caliper is a 1/10 caliper?
On 1/10 calipers, a 9 mm length on the fixed scale (the ruler) is divided into 10 equal parts on the moving scale (the vernier).
When you fully close a caliper’s jaws and the 9th line lines up as shown in the picture above, that caliper is a 1/10 caliper.
1/10 Caliper Reading Examples
The zero point falls between 16 and 17 on the fixed scale = 16.?
Line 7 on the vernier (moving scale) lines up = 0.7
Reading = 16 + 0.7 = 16.7
1/10 Caliper Reading Examples 2
The zero point falls between 13 and 14 on the fixed scale = 13.?
Line 3 on the vernier (moving scale) lines up = 0.3
Reading = 13 + 0.3 = 13.3
Reading a 1/20 Caliper
On 1/20 calipers, a 19 mm length on the fixed scale (the ruler) is divided into 20 equal parts on the moving scale (the vernier).
If the jaws are closed and the 19th line lines up as shown above, we know that caliper is a 1/20 caliper.
1/20 calipers have a precision of 0.05 mm. In other words, this type of caliper can take measurements like 6.25, 7.35, 7.40.
1/20 Caliper Reading Examples
In this 1/20 caliper measurement, we can see the zero point on the moving scale (vernier) has passed 16 on the fixed scale. We determine how much it has passed by finding where a line on the vernier lines up with a line on the fixed scale. Measurement result: 16 + 0.60 = 16.60
1/20 Caliper Reading Examples 2
The zero point sits somewhere after line 14 on the fixed scale.
We can see line 7 on the vernier (moving scale) lines up. The caliper’s precision is 0.05. So, if the spacing between two lines is 0.05 mm, then 7 x 0.05 = 0.35
Measurement result: 14 + 0.35 = 14.35 mm.
1/20 Caliper Reading Examples 3
Reading a 1/50 Caliper
On 1/50 calipers, a 49 mm length on the fixed scale (the ruler) is divided into 50 equal parts on the moving scale (the vernier).
If the jaws are closed and the 49th line lines up as shown above, we know that caliper is a 1/50 caliper.
1/50 calipers have a precision of 0.02 mm. In other words, this type of caliper can take measurements like 6.22, 6.24, 6.28.
1/50 Caliper Reading Examples
Given that the caliper’s precision — the spacing between two lines — is 0.02 mm, the value read on the caliper shown above is 10.42 mm.
1/50 Caliper Reading Examples 2
The zero point starts somewhere after 53 on the fixed scale. Line 17 on the vernier lines up. Given a caliper precision of 0.02 mm, 17 x 0.02 = 0.34
Reading on the caliper: 53 + 0.34 = 53.34 mm.
Caliper Reading Questions and Solutions
We’ve tried to keep the explanations as simple as possible, supported by examples, so that no question marks remain in your mind about 1/10, 1/20, and 1/50 calipers. Even though we think this should be enough, practice will still be needed to reinforce what you’ve learned.
We’ve prepared caliper reading questions and solutions suitable for use in exams at vocational and technical high schools, technical private schools, and vocational training centers that teach in industrial fields. You can find them in the Related Posts section below.
In this article, we’ve tried to put together a page of manual caliper reading lesson notes for anyone wondering how to read a caliper. If you have any questions or would like to add anything about vernier calipers, feel free to share it with us and other readers in the comments section.
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