How to Measure a TV: Simple Measurement Techniques

• Measure the screen diagonally from corner to corner to learn the screen size.
• Measure the height and width of the TV frame to find out if it will fit on your stand or cabinet.
• Place a TV in an area that has a few inches to spare on all sides for proper ventilation.

Find the Dimensions

Measure the screen diagonally from corner to corner. This is how you confirm the manufacturer's advertised size. Regardless of whether you're measuring a flat-screen TV or an old CRT television, start with the end of your tape measure at the top left corner of the screen and extend it to the bottom right corner. Measuring the screen diagonally will give you the standard screen dimension that manufacturers use to advertise the size of their TVs. Some common sizes for TVs based on the diagonal dimensions of the screen include 24 in (61 cm), 28 in (71 cm), 32 in (81 cm), 42 in (110 cm). 48 in (120 cm), 60 in (150 cm), 65 in (170 cm), 70 in (180 cm), and 85 in (220 cm). You can also find TVs with screens as big as 98 in (250 cm) or larger. The largest TV currently on the market for household entertainment is LG's 8K DVLED TV at a whooping 325 in (830 cm).Tip: Only measure the screen itself, not the bezel, or the frame surrounding the screen’s outer edges.

Run your tape measure horizontally from side to side to find the width. This time, measure from the far left edge of the TV to the far right edge, including the bezel on both ends. The number you get will be the overall width, which should be a few inches less than the advertised screen size. For example, a TV listed as 60 in (150 cm) will only be about 52.3 inches (133 cm) wide. Your TV’s width is its most crucial measurement. This is how you can find out if a TV will fit on your stand or cabinet.

Measure from top to bottom to get the height. Now, stretch your tape measure from the upper edge of the TV to the lower edge on the same side. Doing so will give you the overall height. Most newer TVs have a height that’s around 56% of the total width. For example, a TV with a screen that is advertised as 48 in (120 cm) will be about 42 inches (110 cm) wide and have a height of around 25–27 inches (64–69 cm). Generally speaking, height doesn’t matter as much as width. However, the vertical dimension could end up making a difference when you're deciding where to place your TV.

Find the depth of the TV by measuring from front to back. This may be a little tricky if the backside of the TV is tapered. In this case, it can help to hold another long, flat object (such as a yardstick) against the farthest point from the front. Hold it parallel to the screen. Then measure the distance between the screen and the reference object. If that’s not an option, you may also be able to get away with simply eyeballing it. You may need to consider the depth of your TV in order to guarantee that it will fit an existing cabinet or stand. TVs are continually being redesigned to take up less space. These days, many flat screen models are less than 10 inches (25 cm) deep with a stand attached, and as thin as 3 inches (7.6 cm) without. Older CRT televisions are much thicker. You will need to consider the depth with these more than any other TV.

Make Sure the TV Fits

Measure your intended display space. If you haven't already, find the exact height and width of the area where you want to place your TV. If your TV is particularly thick, you may also need to note the depth of cabinets, stands, or entertainment centers to determine whether they're big enough to hold your TV. For maximum accuracy, round off your measurements to the nearest ⁄2 inch (1.3 cm). Jot the dimensions of your display space on a piece of paper and keep them with you when you're shopping around for your new TV.

Allow for an extra 2–3 in (5.1–7.6 cm) of room in your display space. Make sure the stand or section of wall you’ll be placing your TV has a few inches to spare on all sides. That way, you can ensure that it fits comfortably and avoid any unpleasant surprises when it comes time to set it up. Having a few inches of extra space on all sides of your TV allows for proper ventilation, which can prevent performance issues caused by overheating. You’ll need to know your TV’s width and height if you intend to mount it on the wall. If you want to place it on a stand or in an enclosed cabinet, you’ll also need to factor in its depth. When mounting a TV to a wall, be sure to get a wall mount that is rated for the size and weight of your TV. You don't want your TV to fall because it was too big for the wall mount.

Pick out a TV big enough to see clearly from where you’ll be sitting. A 50 in (130 cm) screen may sound impressive, but it could be a little underwhelming if you’re watching from the opposite side of the room. When it comes to arriving at a reliable size estimate, a good rule of thumb is to multiply the distance between your seating area and TV in inches by 0.84. If you’re going to be sitting about 72 inches (180 cm) away from your TV, for instance, a 60 in (150 cm) will provide optimum visibility.

Understand your TV's aspect ratio to enjoy the best picture. The term “aspect ratio” refers to the relation between the width and height of a TV’s display image. Newer widescreen TVs normally have an aspect ratio of 16:9. This means that the picture has a height of 9 inches/cm for every 16 inches/cm of width. Standard TVs tend to be older CRT models. They have an aspect ratio of 4:3. As such, they squeeze the picture into a square image with an overall smaller area, while widescreen TVs take advantage of their added width to display the full image in its proper dimensions. A standard (4:3) TV and a widescreen TV could have the same diagonal screen measurement, but the picture would look quite different for each.

Multiply standard screen sizes by 1.22 to get the same aspect ratio on a widescreen TV. If you’re thinking about upgrading to a widescreen TV but you’d prefer to continue watching in a 4:3 format, multiply the diagonal screen measurement of the old TV by 1.22. The resulting number will tell you how big your new TV would have to be to produce the same size 4:3 image. If you currently have a 40 in (100 cm) standard TV, you’ll need a widescreen TV with a screen that’s at least 50 inches (130 cm) to make sure your picture doesn't get smaller. Standard TVs also have a smaller resolution than new widescreen HDTVs. So the same-size picture on a standard TV will have less detail than on a widescreen HDTV.