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Are TVs Measured Diagonally? (Explained & Solved!)

Antonio Forde
Updated: March 30, 2024
4 min read

Calculating the size of your television is not as complicated as you think. You only need a few seconds at the most.

Read on to find out how televisions are measured.

Here’s How TVs Are Measured:

A television size refers to its diagonal length, stated in inches. You measure from one corner to the opposite corner of the screen surface, top left to bottom right, or vice versa. The number you will get gives you the standard screen dimension television manufacturers use during advertising.

This measurement method is accurate regardless of whether you calculate the dimensions of a flat-screen television or a different model type. 

Standard sizes based on diagonal screen dimensions include 24 inches, 32 inches, 42 inches, 48 inches, and 60 inches.

However, you can find bigger television sizes, such as 72 inches or more. In fact, the biggest television size to date is 292 inches.

Television size measurement only includes the screen itself and not the frame or bezel surrounding the monitor’s outer edges.

Why Are TV Screens Measured Diagonally?

Your television screen is measured diagonally because this is the way screens were initially calculated.

When the first television units were invented, they had bulkier dimensions with less defined images. This was necessary since the cathode ray tube had to be plotted a certain distance between the back and the front screen to operate.

Early television screens were circular because the picture tubes that project images onto the screen followed a round format.

Since the surface area of the television display could not be bigger than the surface area of the picture tube, measuring the tube provided the best method of determining screen size.

The measurement was specified in diameter, which makes sense since you are measuring a circular screen.

As technology continues to improve, televisions become bigger and better. Every year, there is a sleek new model to consider.

Circular picture tubes became rectangular.

What began as a diameter measurement turned into a diagonal measurement, from corner to corner – the largest dimension to be assessed.

Amidst the technological changes, this method of calculating the television screen dimension has stuck around and been utilized on a wide range of screens.

Meanwhile, expressing the size of the television in inches is a standard procedure across the globe.

In the days of cathode ray tubes, the measurement was in centimeters. This changed upon the advent of LCD screens,

During this time, television screen sizes are expressed more in inches, like computer monitors.

While the international standard endorses using the meter as the legal unit of measurement, the inch is still utilized in television technology, computers, smartphones, and tablets.

Using the diagonal measurement is pertinent because the aspect ratio of television screens (width and height) are primarily consistent. 

Older units were mainly 4:3, while most high-definition televisions nowadays have a ratio of 16:9.

If this standard aspect ratio becomes inconsistent, the diagonal screen measurement is no longer applicable. Not to mention, broadcasting will be more complicated as channels consider the wide variety of screen sizes.

As it is, the standardization makes it easy for television manufacturers to market their products to consumers like you.

Presenting only one figure for screen sizes is also simpler. 

However, you should note that the marketed diagonal screen sizes do not always reflect the actual viewable screen sizes. The frame or bezel covers a small portion of the panel.

Frames or bezels are needed to secure television screens. They add structural integrity to the appliance, holding the screen in place and protecting it from damage.

As the technology develops, bezels are getting smaller but still cover extra space. Depending on the model, they can cover the edges of your television screen anywhere from 0.5 to 3 inches.

If your purchased television turns out to be a little smaller than the advertised size, this is normal. 

The bezel is simply covering parts of the screen at the edge.

Knowing the television’s actual width, height, and depth also helps, especially when you plan to fit it into a cabinet or mount it on the wall.

To calculate the width, you run your tape measure horizontally from side to side of the television, including the bezel. For the height, simply measure from top to bottom.

Meanwhile, finding the depth of the television can be tricky, as you will measure from front to back. If your appliance’s rear part is tapered, you may need to be resourceful.

You should always check the dimensions before purchasing televisions. Most manufacturers include all the necessary information on their websites.

If you buy the television in the store, the specifications are readily available on the product box.

You can also bring your trusty tape measure to directly determine the exterior dimensions of the appliance.



Written by
Antonio Forde
I'm the head-writer @ Ask The Home Geek (or, in plain English, I'm the guy writing & editing the majority of the content here). Current learning project: Korean.
Have any questions? Write us a message.
Antonio Forde
I'm the head-writer @ Ask The Home Geek (or, in plain English, I'm the guy writing & editing the majority of the content here). Current learning project: Korean.