How To Read A Micrometer Screw Gauge

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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

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?

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

105 thoughts on “How To Read A Micrometer Screw Gauge”

1. Good explanation , this will help me work with accurate measurements.

2. Rubbissssssssssssssssssssssshhhhhhhhhhhhhhhhhhh!!!!! explanatiooooooooooooooon!!!!!!!

3. Knowledgeable site

4. Thank you for your understanding and brief explanation. It as really assisted me.

• They have really made it so easy, like I was confused but now I’m not

• Am happy this helped a lot.

• I really don’t understand

• same here, I also don’t

5. Thanks,

• They have really made it so easy, like I was confused but now I’m not

6. Thank you for brief and understanding explanation

7. You make it easy thanks for your explanations I really appreciate

8. I have seen this particular question (same picture) about a micrometer in the exam but the answer 2.88 mm was not in the choices. How is that?

• Because their retards

9. A really helpful site to get going with the concepts.

10. You guys just made is a smple as this

11. Need some explanation on how to get the zero errors… Thank you.

• its usually caused by faulty instruments

12. Thankyou.Easy to understand.

13. My homework really confused me since we had never been taught how to do this ‘zero error thing’. Your assistance was a great relief.
Thanks alot😄

• exactly

14. am confidently sure that,am gonna pass my exam tomorrow, thanks for this,you made it so simple for a one day baby to understand🙏

15. Thanks very much.this has helped me with my assignments

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

17. Best explaination I found while searching for it

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

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

• This is an excellent explanation

19. 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.

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

21. 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!

22. Nice work in very simple words thanks????

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

24. Actual reading for you thanks best of lock

25. very good because it is easy for student to understand

26. Wow very nice plz tech me very esy topics

27. The concept for screw measurement reading explains very well. All of us know that the micrometer screw gauge is a small but very essential measuring device.

28. where is the least count ? I’m confused

29. A lot of thanks for making such a good website.I could easily understand the working of screw gauge.it’s the best for PHYSICS

30. That Is great i like it so much….

31. thanks that is so interested

32. Very good

33. nice one, moreover I like it very much.

34. definitely agreeing…

35. This really helps

36. I like this website very much,the description is more detail and understandable

• Say, correctly, : …more detailED…

37. I luv dis website <3

38. made me understand physics better :))

39. what is applications of micro meter screw gauge

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

41. Very educative, simple and precise

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

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

43. the notes are well summarized(short and clear) and understandable

44. This is in the range of good not in the range of outstanding.

45. Very easy to understand..kip it up!

46. tnx alot the simulator was very useful

• Just convert from mm to cm?

48. Now it’s easy to understand

49. It’s awesome and very help for me to understand

50. i really found it easy to understand

51. Thank u so much …it helped me alott!!..

52. awesome thanks……..

53. I really found it easy to understand

54. thanks alot its really helpful

55. Hoping to learn much more from this web……Thanks alot.

56. Here I am again! From vernier calliper to micrometer… Wish me luck in my exam today!!!

57. After reading it now I can perfectly use a screw guage….Thanks alot

58. I have created a HTML 5 simulation.
Check it out. It even has a zero error.
Micrometer Model
Enjoy

• Wow! Brilliant work!

59. nice way to explain……..

60. Thank u sooo much i enjoyed it

• I also enjoyed it

61. Yeah dude totally helpful i was so scared that i wouldnt know how to use this.
Im a chef btw.

62. Thanks much I enjoyed it

63. I still don’t get it please put in more emphasis especially on the reading aspect and also the calculation. i want to know how read the guage well so pictures and teaching programmes

• There are plans to expand this post. Please keep a look out for it. 🙂

64. isn`t the second part is measured by multiplying the least count with thimble scale reading?
and so it should be 0.001×38=0.038……….. confused please explain

• The least count is 0.01 mm. Hence it is 0.01 mm X 38 = 0.38.

65. nice…. but i needed smthng else 😉

66. Thank u for such a great thing

67. Dear sir
You should give some more examples
Thanks

68. i have like your teaching because its uery easy to understand

• Agreed*

70. Since the least count of screw gauge is 0.001cm, the reading must come in same way for example 1.762

• All of the readings are in mm.

71. How can we remove the zero error?

• You can “remove” the zero error by using the calculation method above.

Alternatively, you can remove the zero error (permanently) by re-calibrating (re-zero’ing) the micrometer screw gauge by using a micrometer spanner wrench.

In the school setting, zero error in micrometer screw gauge is due to the students’ mis-handling of the micrometer screw gauge. (E.g. Over-tightening of the micrometer screw gauge)

• I don’t understand what actually the zero error is. :/