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

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

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 answers

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, please click the navigational buttons below to go to the next page. There is a **very useful** simulation of the micrometer screw gauge.

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

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scribbles scribbled

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chaudhary ritik raj scribbled

what is applications of micro meter screw gauge

saquib tanwar scribbled

The above information can be easily understood it is written in easy language

Cosam scribbled

Very educative, simple and precise

laiba mohsin scribbled

good

but i need to know how to find reading on screw gauge if the zero is above the datum line

plzzz must reply

akshatarani scribbled

if zero is above the datum line than the value of will be negative that is 0-the coincided number

mteleke peter angelo scribbled

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Sanjay kc scribbled

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Raul scribbled

I have to agree. Plenty of proffessional online animations explaining the procedure. This can be improved.

laiba mohsin scribbled

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ritu scribbled

yes i agree

Lawrence Wee scribbled

Get my new Android micrometer app here.

https://play.google.com/store/apps/details?id=com.ionicframework.micrometerapp268865

Enjoy!

Mini Physics scribbled

Thank you for your contributions to the Physics community. Your link has been added to the main post. 🙂