How to Read a Metric Micrometer

If you can read this one you are done.  You pretty much owned this tutorial.  Give it a try…

The reading is 11.72 mm.  If you got that, way to go!  Let’s break it down:  First the barrel.  10 is the biggest number showing, so count over from there to 11, but notice the half mark is the last mark displayed.  This means the barrel scale is reading 11.5.  If you don’t see it, look under the horizontal line.  Now write down 11.50 (it’s best to write down two decimal places to keep everything consistent.
Now look at the thimble, 0.20 is the last printed number, so count up from there to 0.22 and write that down. Now add them up and you get 11.72 mm.

Only one more concept and we are done. What if one of the marks on the barrel scale is just barely showing.  Do you count it?  Is it ready to be used? Here is the  trick: Don’t look at the mark to find out whether the mark is showing or not… Look at the thimble.  You need to know if a new mark is starting or an old mark is ending.  In this example, look at how big the number on the thimble is.

It is showing about .47mm.  That is a big number (the scale only goes up to 49).  Since the scale is nearing the end, it’s “ending” you don’t count a mark that is barely showing. The trick is to find which side of zero you are working on.  Not yet to zero, not yet a mark.  In the drawing below, I moved the micrometer a little bit.  Now the, the mark is ready to be counted because the thimble scale is “starting.”

You see that the numbers on the thimble are small because the zero just passed by.  This means the mark is ready to be used. So that’s pretty much it. There are some micrometers that can measure even more accurately than this, they have a thing called a “vernier” scale on them.  I can show you how to read those another time if you want.  Just let me know.  But for now this should get you started.