A quick guide on how to read a vernier caliper. A vernier caliper outputs measurement readings in **centimetres (cm)** and it is precise up to 2 decimal places (E.g. 1.23 cm).

**Note:** The measurement-reading technique described in this post will be similar for vernier calipers which output measurement readings in inches.

### Measurement Reading Technique For Vernier Caliper

In order to read the measurement readings from vernier caliper properly, you need to remember two things before we start. For example, if a vernier caliper output a measurement reading of **2.13 cm**, this means that:

- The
**main scale**contributes the main number(s) and one decimal place to the reading (E.g. 2.1 cm, whereby 2 is the main number and 0.1 is the one decimal place number) - The
**vernier scale**contributes the second decimal place to the reading (E.g. 0.03 cm)

Let’s examine the image of the vernier caliper readings above. We will just use a two steps method to get the measurement reading from this:

- To obtain the
**main scale**reading: Look at the image above, 2.1 cm is to the**immediate left of the zero**on the vernier scale. Hence, the main scale reading is 2.1 cm - To obtain the
**vernier scale**reading: Look at the image above and look closely for an**alignment of the scale lines**of the main scale and vernier scale. In the image above, the aligned line correspond to 3. Hence, the vernier scale reading is 0.03 cm.

In order to obtain the **final measurement reading**, we will add the main scale reading and vernier scale reading together. This will give 2.1 cm + 0.03 cm = 2.13 cm.

Let’s go through another example to ensure that you understand the above steps:

**Main scale** reading: 10.0 cm (Immediate left of zero)

**Vernier scale** reading: 0.02 cm (Alignment of scale lines)

**Measurement reading**: 10.02 cm

### Compensating For Zero Error

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

The reading on the top is the measurement obtained and the reading at the bottom 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: 3.34 cm

Zero error: – 0.04 cm (negative because the vernier scale is to the left)

Measurement without zero error: $3.34 \, – ( \, – 0.04) = 3.38$ cm

If you do not understand the subtraction of the negative zero error from the measurement, please read on. Since the zero error is -0.04 cm, this means that all measurements taken by the vernier calipers will be *SMALLER* by 0.04 cm. Hence, you will have to *ADD* 0.04 cm to *ALL* measurements in order to get the *TRUE* measurement. The subtraction is done in the above case is to have an elegant way of obtaining a resultant addition: $3.34 + 0.04 = 3.38$ and to make it *COMPATIBLE* with positive zero error. This means that once you have determined the nature of the zero error (positive or negative), you can just subtract the zero error and be sure that your final answer is correct.

Consider a zero error of +0.04 cm. With my method, $3.34 \, – (+ 0.04) = 3.30$ cm.

**Normal method:** Since the zero error is +0.04 cm, this means that all measurements taken by the vernier calipers will be larger by 0.04 cm. Hence, you will have to *SUBTRACT* 0.04 cm from *ALL* measurements in order to get the true measurement. The final calculation will be $3.34 \, – 0.04 = 3.30$ cm, which is the same as my method.

**Note:** I hope that I did not confuse you. Drop a comment below if you encounter any difficulties.

**More Vernier Caliper Practice:**

### Self-Test Questions For Vernier Calipers

**Where on the vernier calipers would you read to obtain the main scale reading?**

### Show/hide answers

The main scale reading is obtained from the reading on the main scale that is at the** immediate left of the zero** on the vernier scale.

**Where on the vernier calipers would you read to obtain the vernier scale reading?**

### Show/hide answers

The vernier scale reading is obtained from the reading on the main scale that has an **alignment of the scale lines** of the main scale and vernier scale.

**What is the smallest possible reading (in cm) of a vernier caliper?**

### Show/hide answers

The smallest possible reading of a vernier caliper is 0.01 cm.

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 vernier calipers.

Dee karia scribbled

I think there something wrong with that zero error….it should be -0.06 not -0.04

Chris Delmar scribbled

Thanks for this… I would like to clarify one thing: when you read the negative zero error, it seems that you are counting backwards from the right-most mark on the Vernier scale (four ticks) instead of forwards from the left (six ticks) on a normal measurement. Can you please confirm?

Stewart scribbled

I’m with Ken. How are you calculating that your zero error is -0.04?

Osemeahon lucky scribbled

Please like this question how can I solve it.

A venier measures a distance of 1.17cm and the main scale reads 1.1cm . Draw and discover the venier scale reading

Khushi scribbled

You had helped me a lot … Tomorrow is my practical … Thanks a lot ….

Ken Francis scribbled

I am a Physics teacher. Inexplicably, some of your answers seem wrong to me. Above, and in two of the practice examples (next page). Eg, above, the zero reading is -0.06, surely, not -0.04. What am I missing?

Ivan scribbled

this comment saved me i was terribly confused on how he arrived at the zero error

Fahad scribbled

Hi ivan, i just wanted to ask that when you will stack up 20 pieces of paper and measure them with either vernier calliper or micrometer screw guage and get the reading and divide it with the number of pieces of paper you have taken measure of, will you read only the main scale or both scales on either both instruments

Seth T Ashman scribbled

First look at the main scale and imagine additional lines to the left of zero, i.e. -0.1, -0.2, etc. Then if you read the caliper in the usual way, the Vernier scale zero lies to the right of the -0.1, so that is our “main scale” reading. Next you need to add the measurement from the Vernier scale, which as you mention is 0.06. This results in the “zero reading” in this case of -0.1 + 0.06 = -0.04.

pujj scribbled

thank you so much<3