A quick guide on how to read a micrometer screw gauge. Similar to the way a vernier caliper is read, a micrometer reading contains two parts:

- the first part is contributed by the main scale on the sleeve
- the second part is contributed by the rotating vernier scale on the thimble

**Sponsored Link**: Want to play around with a real micrometer screw gauge? Click here to get from Amazon!

## Measurement Reading Technique For Micrometer

The above image shows a typical micrometer screw gauge and how to read it. Steps:

- To obtain the first part of the measurement: Look at the image above, you will see a number 5 to the immediate left of the thimble. This means 5.0 mm. Notice that there is an extra line below the datum line, this represents an additional 0.5 mm. So the first part of the measurement is $5.0 + 0.5 = 5.5$ mm.
- To obtain the second part of the measurement: Look at the image above, the number 28 on the rotating vernier scale coincides with the datum line on the sleeve. Hence, 0.28 mm is the second part of the measurement.

You just have to add the first part and second part of the measurement to obtain the micrometer reading: $5.5 + 0.28 = 5.78$ mm.

To ensure that you understand the steps above, here’s one more example:

First part of the measurement: 2.5 mm

Second part of the measurement: 0.38 mm

Final measurement: 2.88 mm

## Compensating For Zero Error

### In a nutshell

Use the following formula:

$$\text{Correct reading} = \text{Obtained reading} \, – \, \text{Zero error}$$

where $\text{zero error}$ can be either **negative** (the “0” marking on the thimble is **above** the datum line) or **positive** ( the “0” marking on the thimble is **below** the datum line )

### Explanation

Now, we shall try with zero error. If you are not familiar on how to handle zero error for micrometer screw gauge, I suggest that you read up on Measurement of Length.

The reading on the bottom is the measurement obtained and the reading at the top is the zero error. Find the actual measurement. (Meaning: get rid of the zero error in the measurement or take into account the zero error)

Measurement with zero error: 1.76 mm

Zero error: + 0.01 mm (positive because the zero marking on the thimble is below the datum line)

Measurement without zero error: $1.76 \, – (+ 0.01) = 1.75$ mm

The subtraction logic is similar to the method explained in How to read a vernier caliper. You can take a look and comment below, if you encounter any difficulties.

### Self-Test Questions

**What is the smallest possible reading (in mm) on the thimble scale? What is the biggest possible reading?**

**Show/Hide Answer**

The smallest possible reading on the thimble scale is 0.01 mm, while the biggest possible reading is 0.49 mm.

If you still do not understand the concept, there is a **very useful** simulation of the micrometer screw gauge here.

**Bonus:** You can get this micrometer app on your mobile phone (Android): https://www.miniphysics.com/link/micrometerapp

Thanks very much.this has helped me with my assignments

The above explanation made me understand how to use the micrometer crewgauge very well.

Best explaination I found while searching for it

Yayy i finally understood how to read a screw gauge le!!:))

this is really helpful now i know how to read a micrometer screw guage THANK YOU

This is an excellent explanation

The examples shown are really helpfull some how it helps me with my studies back at university of south pacific. THANK YOU..Hope to see more of examples from this pages …thanks that much.

Am really grateful for making me understand micrometer so well. THANK YOU!

Really simply explained! I quickly searched for how to read the micrometer screwgauge before my practical physics exams, and this post ABSOLUTELY nailed it! Thank you!

Nice work in very simple words thanks????

i really wanted to know much about your work.I hope you will get back to me soon

Actual reading for you thanks best of lock