From corner to corner – that’s how you measure the size of a TV screen. You use a tape measure on the screen itself, not the plastic frame around it, to get the true diagonal length in inches.
This is the standard way all TVs are sized. seems simple, but many people get it wrong. They include the bezel or measure the wrong way.
I’ve helped friends buy TVs for years. The wrong size can ruin your viewing setup. A 65-inch TV is not 65 inches wide.
This guide will show you the right way. I’ll cover measuring for a new spot, checking an old TV, and avoiding common mistakes.
What Does TV Screen Size Really Mean?
When stores say “65-inch TV,” they mean one thing. They are talking about the diagonal screen length.
This number comes from measuring the glass picture area. You start at one bottom corner and go to the opposite top corner.
The plastic frame around the screen does not count. This frame is called the bezel. Bezels can be thin or thick, but they are not part of the screen size.
So how do you measure the size of a TV for real? You ignore the bezel completely. Focus only on the lit-up area where the picture shows.
This standard makes shopping easier. You can compare different brands fairly. A 55-inch Samsung and a 55-inch LG have the same viewing area.
The Tech Terms dictionary confirms this is the industry standard. All manufacturers use the diagonal measurement.
The Step-by-Step Guide to Measuring Your TV
Grab a soft tape measure. A fabric one works best so you don’t scratch the screen.
Place the end of the tape at the bottom left corner of the visible screen. Stretch it diagonally to the top right corner. Read the number in inches.
That’s your screen size. It’s that simple. How do you measure the size of a TV if it’s already on the wall? Use the same method carefully.
You might need a step stool. Make sure the tape is flat against the screen. Do not let it sag in the middle.
Write the number down. Now you know your true TV size. This is helpful for buying a replacement or a matching stand.
I measured my own TV last week. I thought it was a 50-inch model. It turned out to be only 48 inches!
Measuring for a New TV Stand or Wall Space
Screen size is not the only number you need. You must also measure the TV’s total width and height.
This includes the bezels. How do you measure the size of a TV for a cabinet? You need the full width with the frame.
Use your tape measure across the entire TV from left edge to right edge. Do this at the widest point, which is usually the middle.
Then measure the full height from the very bottom to the very top. Include any stands or feet if they are attached.
These numbers tell you if the TV will fit your furniture. A 65-inch screen might need a 58-inch wide stand. Check your cabinet first.
The Consumer Reports buying guide stresses this step. Always check the full dimensions, not just the screen size.
I learned this the hard way. My new TV’s feet were wider than my old stand. I had to buy a new one.
Common Mistakes People Make When Measuring
The biggest error is measuring the wrong part. People measure the bezel and think that’s the size.
Another mistake is measuring horizontally. They go from left to right across the screen. This gives the width, not the screen size.
How do you measure the size of a TV without these errors? Remember: diagonal and screen-only. Say it to yourself as you do it.
Some people use a ruler instead of a tape measure. A ruler cannot bend across the diagonal. You will not get an accurate number.
Also, don’t measure with the TV on. The bright light can make it hard to see the screen’s edge. Turn the TV off first.
I’ve seen folks guess based on the model number. This is not reliable. Always take the time to measure it yourself.
You might be surprised. An old “42-inch” TV might actually be 40 inches. Models were rounded up sometimes.
Why the Diagonal Measurement is Used
This method started with old cathode ray tube TVs. The round tubes were measured diagonally. The habit stuck for flat screens.
It gives a single number for comparison. Width and height change with different screen shapes, or aspect ratios.
How do you measure the size of a TV fairly if one is wider? The diagonal measurement standardizes it. A 16:9 screen and a 4:3 screen of the same diagonal have different widths.
It’s also the most impressive number. A bigger diagonal sounds better to buyers. It’s the main number you see in ads.
The Consumer Technology Association sets these standards. They keep the industry consistent for shoppers.
Think of it like pizza. You order a 16-inch pizza. You don’t order by its width or how much area it covers.
It’s just the way it’s done. Knowing this helps you shop smarter. You understand what you’re really getting.
How to Measure a TV That’s Curved
Curved TVs can be tricky. Do you measure along the curve or in a straight line?
You measure in a straight line. How do you measure the size of a TV with a curved screen? Use a string first.
Place a string from the bottom corner to the top corner, following the curve. Mark where the string meets the opposite corner.
Then lay the string flat and measure it with your tape measure. This gives you the diagonal screen size along the curve.
Most manufacturers list the straight-line diagonal, though. Check the manual to be sure. When in doubt, use the straight-line method.
The curve doesn’t add much size. A 65-inch curved TV and a 65-inch flat TV have very similar diagonal lengths.
I measured a friend’s curved Samsung. The curved diagonal was about half an inch longer. It was not a big difference.
Using TV Size to Choose the Right Viewing Distance
Your screen size tells you how far to sit. This is key for a good experience.
A simple rule is the 1.5 to 2.5 times rule. Multiply your screen size in inches by 1.5 and 2.5.
For a 60-inch TV, that’s 90 to 150 inches away. Convert that to feet by dividing by 12. So sit 7.5 to 12.5 feet away.
How do you measure the size of a TV for this calculation? Use the true diagonal you found. Then measure from your screen to your couch.
Sitting too close can make the picture look pixelated. Sitting too far wastes the detail. Find your sweet spot.
The Rtings.com experts have detailed charts. They consider resolution too. A 4K TV lets you sit closer than an HD TV.
I moved my couch back two feet after measuring my new 70-inch TV. The action movies look much better now.
What About the Box or Manual? Can You Trust Them?
The box should have the right size. But mistakes happen in printing or labeling.
If you have the manual, check the specifications page. Look for “display size” or “screen size diagonal.”
How do you measure the size of a TV to confirm the box is right? Just do your own check. It takes two minutes.
Sometimes a model is listed as “55-inch class.” This means it’s around 55 inches. It could be 54.6 or 55.2.
Manufacturers round to the nearest whole number. Your own measurement will give you the exact figure.
I trust the tape measure more than the box. It’s the ground truth for your specific TV.
This is especially true for older or used TVs. The box is long gone. Your tape measure is your best friend.
Tools That Can Help You Measure Accurately
A soft, retractable fabric tape measure is the best tool. It’s flexible and won’t damage the screen.
Don’t use a metal carpenter’s tape. The edge can scratch the TV surface. Be gentle.
How do you measure the size of a TV if you don’t have a tape? Use a piece of string and a ruler.
Run the string diagonally. Mark the endpoints on the string. Then lay the string next to a ruler.
There are also smartphone apps that use the camera. They can be less accurate. I don’t recommend them for something this important.
For a TV on the wall, a second person helps. They can hold one end of the tape steady. This stops it from slipping.
Keep a notepad handy. Write down the diagonal, the width, and the height. This info is useful for many things.
Frequently Asked Questions
How do you measure the size of a TV in centimeters?
Use the same diagonal method. Just read your tape measure in centimeters instead of inches. One inch equals 2.54 centimeters.
Is a 55-inch TV actually 55 inches?
Usually, yes. But it might be 54.8 or 55.1 inches. “55-inch” is the rounded marketing name for that size class.
How do you measure the size of a TV for the wall mount?
You need the VESA pattern measurements. This is the distance between the mounting holes on the back of the TV, not the screen size.
Does the screen size include the black bars in movies?
No. You measure the entire lit rectangular area. The black bars are part of the video signal, not the physical screen.
How do you measure the size of a TV that’s broken?
You can still measure the screen glass. Be careful of sharp edges. The method is the same if the screen is intact.
Why is my TV’s model number different from its size?
The model number is a code for the series and features. The screen size is just one part of that. Always measure to be sure.
Conclusion
So, how do you measure the size of a TV? You go from corner to corner on the screen itself.
Remember the diagonal rule. Ignore the bezel. Use a soft tape measure for safety.
Now you can shop with confidence. You can set up your room perfectly. You won’t be fooled by marketing talk.
Grab your tape and check your TV now. You might learn something new about your own screen. Happy measuring!