Measuing the Diagonal Dimensions of a TV set

Sometimes you own a TV set and don’t know what size it is, or you need to measure a TV to see where it will fit. Either way, there are a few ways to do it, and we’ll show you how.

How to Measure Your TV’s Screen

TV sets are usually sold by screen size, which is a number in inches. Manufacturers obtain this number by measuring across the diagonal distance from one corner of the viewable screen area to the opposite corner.

Different TV sizes with diagonal measurements compared.

To measure the diagonal of a TV screen, you will need a tape measure and a helper. With the TV turned off, have your helper hold one end of the tape measure at the top left corner of the screen. Measure from the top left corner to the bottom right corner of the screen, ignoring the bezel. This is the TV’s diagonal measurement—and its conventional screen size.

How to Measure Your TV Set’s Dimensions

Another way to measure the size of the TV screen is by using its actual dimensions of width, height, and depth. This type of measurement includes more than just the surface of the TV screen, so it’s a more accurate reflection of how much space the TV set will take up in your room.

Someone measuring the height of a TV set with a tape measure.
TY Lim/

To measure the width, height, and depth of a TV set, you will need a tape measure again. Hold one end of the tape measure at the top left edge of the TV set’s body. Measure horizontally across the TV to the opposite side, keeping the tape measure parallel to the top edge of the TV set. This is the TV’s width.

Next, do the same thing except measure from the bottom edge to the top edge of the TV set, keeping the tape measure parallel to the left and right sides of the TV. This is the TV’s height. Finally, measure the depth by measuring from the front of the screen to the back of the TV.

With these dimensions in hand, you can shop for a proper TV stand or mount that is the right size for your TV set. Or you can measure empty spaces in your room to see if the TV will fit. Just remember: don’t put your TV over the fireplace, or you might experience neck strain.

What Size TV Do I Need?

When it comes to choosing a TV size, some people like a smaller TV and some like a bigger TV. Much of your choice will come down to personal preference, although the ideal TV size also depends on how far you’ll be sitting from it when you watch.

We’ve written a detailed guide on how to choose the right TV size for your room, but put simply, if your room is small, you might want a small TV. If your TV room is huge and you are sitting farther away from the screen, you might want a larger TV. If you have trouble seeing detail in video games, you might want a larger screen even if your room is relatively small.

Opinions vary about the proper formula for calculating TV viewing distance, but one rule of thumb for TV size and placement (that Sony mentions on its website) is that the ideal viewing distance from the screen for a high-definition TV is 3 times the height of the TV screen. Measure the distance between where you’ll be sitting and where you’ll place the TV, then divide by 3. That will give you the vertical (not diagonal) screen size of the TV you need for that room in inches, and it’s helpful information to have when shopping for a new TV. Good luck, and happy watching!

The Best TVs of 2022

Best TV Overall
Samsung S95B
Best Budget TV
Hisense U6H
Best 8K TV
Samsung QN900B
Best Gaming TV
Best TV for Movies
Sony A95K
Best Roku TV
TCL 6-Series R635
Hisense U8H
Profile Photo for Benj Edwards Benj Edwards
Benj Edwards is a former Associate Editor for How-To Geek. Now, he is an AI and Machine Learning Reporter for Ars Technica. For over 15 years, he has written about technology and tech history for sites such as The Atlantic, Fast Company, PCMag, PCWorld, Macworld, Ars Technica, and Wired. In 2005, he created Vintage Computing and Gaming, a blog devoted to tech history. He also created The Culture of Tech podcast and regularly contributes to the Retronauts retrogaming podcast.
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