How is a TV measured to determine screen size

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Bernard Perron
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Imagine spending months looking for a quality TV for your home entertainment room. You finally buy the TV you want at an affordable price. When it is installed, you are disappointed. He seems to be out of place in the room. This may happen because you didn't know how screen size correlates to actual TV size.

There is a process for measuring the screen size of a TV. Read on to learn more about how TVs are measured so you can choose the right size for a space.



How to measure a TV screen?

Balance is key when considering placing a TV in a room. Don't be tempted to buy the biggest TV if the room is small. Likewise, it's not a good idea to save money by buying a small TV for a large room. The main TV size guidelines for common media rooms are:

  • 60 to 90 inches for home theaters
  • 50 to 64 inches for large living rooms or family rooms
  • 33 to 49 inches for medium living rooms or large bedrooms
  • 32 inches or less for medium rooms
  • 32 inches or less in kitchens, dorm rooms and small apartments

Although these are suggested guidelines, the final choice of your screen size is entirely up to you. If you like watching movies on "larger than life" screens, don't be afraid to buy the biggest TV you can afford. What is important is that you know how to properly measure a TV screen before you buy the TV so that it fits the room correctly.


There are three key factors you need to know when taking measurements on a TV screen. They are:


  • The size of the visible screen
  • The dimensions of the frame or bezel
  • The size of the space where the TV will be placed

All screen sizes are listed in inches. The numbers represent the diagonal measurement from the upper left corner to the lower right corner. You must measure the screen diagonally to get the correct size. TV screens were originally measured diagonally because:

  • They had round picture tubes that projected images onto the screen.
  • The screen could not be bigger than the circular tube.
  • The tube measurement provided the screen measurement.

Expressing the size of a television screen in this way remains standard practice. However, not all of the advertised screen size is "viewable" because a small portion of the screen is covered by a bezel or bezel. However, store advertisements include the bezel in the diagonal measurements of the TV screen size.

The part of the screen where you actually see the image is slightly smaller. TV screen bezels are typically between ½ and 3 inches wide, but frame widths vary with each TV manufacturer. This creates gaps between the total screen size and the visible screen size. Below are examples of some advertised diagonal screens compared to their actual screen sizes.

  • Ad 40 inches, actual size 39,9 inches
  • Advertised 55 inches, actual size 54,6 inches
  • Ad 65 inches, actual size 64,5 inches
  • Advertised 75 inches, actual size 74,5 inches

You may have seen the word "class" in a TV commercial. For example, an ad might list a 70-inch "class TV". This term is used because the frame must cover a small part of the panel to secure it. Stores use the word "class" to combat claims of false advertising.



If you're considering buying a TV, here's how to measure the screen:

  • Install a measurement app on your mobile device. They are available on Android and iOS.
  • The TV you want to buy may be on display in the store. Use a tape measure and place it diagonally across the screen in the frame.
  • Carefully read the manufacturer's product specifications, which are usually found on the outside of the box.
  • Research the make, make, and model of the TV online. Specifications will be on the manufacturer's or retailer's website.

When shopping for a television, it's a good idea to keep a tape measure with you so you can also measure the overall height, depth, and width of the televisions. These measurements can help you determine if the TV will fit in the space you intend to place it.

Buying a new TV isn't the only reason you might need to measure it.

Maybe you need to know how to measure the screen on a TV you already own to sell, or you're planning on moving it to another location in your home. You can calculate your TV screen in several ways, for example:

  • Install the latest measurement app on your mobile device.
  • Consult your owner's manual for screen measurements.
  • Search online for make, make, and model to get specs.
  • Measure by attaching a tape measure diagonally across the screen.

You can also use everyday items found around your house if you don't have a tape measure. Try these items at a glance:



  • Tape sheets of standard 11-inch printer paper diagonally across the screen to calculate the measurement.
  • A dollar bill is exactly 6 inches long. Use paper money to measure the screen diagonally.
  • Use a ruler to measure the screen. Be sure to protect the screen from scratches.
  • Place a string or rope across the screen diagonally and mark the distance between the bezel. Use another pre-measured household item to measure the twine.

Don't take the risk of having to uninstall and move a wall-mounted TV. Learn how to take measurements of your screen in certain areas to mount it correctly the first time. Wall-mounted TVs should be placed at the correct eye level for optimal viewing comfort.

For example, most action movies take place in the middle third of the screen. To make sure you don't miss any of the action, measure your TV so that your eyes are level with this area when you're seated. Check out these tips before setting up your TV:

  • Measure the height of your screen to find out where the middle of the screen is.
  • Measure the width of your screen to ensure you purchase the correct wall mount.
  • Measure the size of the visible screen to choose the best location in the room to mount it.

Measuring a TV projector screen is a unique process. The aspect ratio of the screen may depend on the purpose of the display. Common projection screen ratios include:

  • 4:3 for general settings like watching movies
  • 4:3 for classrooms or meeting rooms
  • 16:9 for viewing in HD
  • 16:10 p.m. to see it on the big screen

You may already have a projection TV for home entertainment. Here's how to measure a TV projector screen if you're considering replacing it:

  1. Measure the length of the screen from the top left corner to the bottom right corner (like a regular TV screen).
  2. Change your aspect ratio to a fraction (eg 6:19 would be 16:9).
  3. Measure the width of the screen.
  4. Multiply it by the fraction to get the height.
  5. Add height2 plus width2. This is equivalent to diagonal2.

The square root of this number is the diagonal measurement of your TV projector screen, based on the Pythagorean theorem (un2+b2=c2).

Home Entertainment in "You" Size

Your home entertainment space is a relaxing environment, and the TV is the centerpiece. There are no hard and fast rules regarding screen size; it is your personal choice. However, there are some general guidelines that can help you ensure the perfect fit.

Do you watch television? Let us know how often you watch TV. Include the size of your largest TV. Use the comment box below for your response.

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