All TVs are measured diagonally from one lower corner to the opposite upper corner. That's the measurement listed on the box and is normally a reliable method of comparing TV sizes. It breaks down, however, when comparing older tube screen TVs (which use a 4:3 screen ratio) and newer projection or flat-screen TVs (which use a wider and narrower 16:9 ratio). Accordingly, a "larger" flat screen TV may actually contain fewer square inches than a "smaller" analog TV! Here's the best way to accurately measure the difference when buying a big screen TV.
Instructions
1. Measure the space you'll need for your big screen TV before you buy. Knowing how much room you have to play with helps you determine what size television works best. Write down the depth you have, as well as the height and width. Leave at least 6 inches of space between the TV and any pictures, windows or furniture in the area.
2. Determine all of the dimensions on the new TV and make sure they fit in with the space you have set aside. Don't just use the big measurement on the box: get the size of the frame and tube as well. This probably won't be a problem with flat-screen TVs, which are very thin and don't extend out much beyond their screen. Projection TVs and older analog TVs, however, should have their whole size measured carefully.
3. Compare the height of the new TV's screen to the height of the older TV, especially if you are trading in a TV with a 4:3 screen for one with a 16:9 screen. That ensures that the new TV is at least as big as the old one (and probably a little bigger). If you just go by diagonal width, you'll probably end up with a smaller screen size.
4. For a fast measurement shortcut, multiply the diagonal width of an old 4:3 ratio TV by 1.22. The result is the required diagonal width of a new 16:9 ratio TV to match the size of the old set. Since the diagonal width is the one listed on the box and in the ads, you can make the calculations instantly without relying on a tape measure.
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