How to measure monitor Size – 3 Simple Steps!

Whenever we look up desktops, laptops, TVs, etc online, they usually specify the display size. For example, we know that the Apple MacBook Air comes with a 13.3-inch screen.


So, what is the simplest way to measure a monitor size?

To measure a monitor size

1. Take a tape measure and gauge the diagonal length of the display area.

2. You need to measure it from one corner of the screen to the opposite diagonal end of the screen. This will give you an accurate screen size.


The other fast and easy way to find out your monitor size is by searching for the model online!

Google the model number and you will get the size. And then there are many websites that will help you find out the monitor size as well!

Steps to measure monitor size

For a CRT Display

Yes, it is not very likely that you are using the old tech CRT display but some people and organizations still do use them.

To measure the display size of a CRT monitor requires a different approach than measuring the size of the newer displays.


You will need to take a tape measure and check the length from one corner of the monitor, including the non-display portion, diagonally to the corner of the other end.

For an LCD/LED display

If you want to find out the display size for any non-CRT display then the process is very straightforward

. You will need to measure the diagonal length of the display to find out the size.

How to measure monitor size

On the display, exclude the casing and just measure the screen from one end to the other diagonal end.

Use the same steps to measure the size of your TV, laptop, desktop, or any other electronic equipment that has a display built into it.

Methods of calculating display area

There are many lines of thought about what the definition of display size actually is.

If you are looking to invest a good amount of money in displays then you will need to know a bit more about the size calculation.

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Calculating the Monitor Size

The Nominal Size of a display is one of the most common methods of calculating its size. This is the diagonal length measured from one corner of the monitor area to the opposite end.

Calculating the Viewable Area

The viewable area is actually the display part. It will always be lesser than the Nominal size of the monitor as it doesn’t include the size of the casing.

This is calculated by measuring one corner of the display area to the diagonal end of the display area.

Calculating the Aspect Ratio

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For some users, the most important size metric is the aspect ratio. This doesn’t directly correlate to the size of the monitor but the layout and design factor.

The aspect ratio tells us the relationship between the length and the width of the monitor. The most common ones are the 4:3 for a standard display and the 16:9 for a widescreen display.

Calculating the Image area

If you are interested in calculating the total area of the display or image area then you will need to follow two steps.

  • First, take a tape measure and calculate the length of the display (not monitor)
  • Then measure the height of the display
  • Multiplying both will give you the total display area

Frequently Asked Questions

You might have additional questions related to measuring monitor size, so we have listed some of the most commonly asked queries below.

How can I check the monitor size without physically measuring it?

You can do this by looking up the monitor model online. Search for the monitor model and you should get the display size. Or you could also check it in the Setting – Display section in Windows. In macOS, you will get the information under the ‘About this Mac’ option.

Can I use online tools to check my monitor size?

Yes, there are some websites that can recognize your monitor size. In Google, you can search for ‘measure my laptop size online’ and you will see lots of options.

Is the monitor size the same as the aspect ratio?

No. The aspect ratio is basically the orientation or the relationship of the length and the height of the monitor. For example. you can have a standard or a widescreen monitor.


Every monitor or display seller or manufacturer lists the size of the monitor being sold. You will find this information in your product manual and in the System Settings as well.

But, if for some reason you still want to manually measure your monitor size, you can use the guidelines provided in this article.