To find out how many inches your TV screen is, measure the distance from the upper left corner to the lower right corner, or from the lower left corner to the upper right corner. It doesn't matter which one, because the measurement will be the same. Measure only the visible screen, not the frame around the edge of the screen.
It depends on two things: Screen resolution and how many metres there are between where you sit and where the TV will be. Use our Distance to TV calculator to get an accurate calculation.
If you buy a screen that is too big and sit too close to the TV, you may also find that the picture is blurred or that it is difficult to see all the details. This can make the viewing experience worse, even if the TV is otherwise of high quality.
It is therefore important to choose a screen size that suits the distance between you and the TV so that you can have a comfortable viewing experience without discomfort or poor picture quality.
As a rule of thumb, the centre of the TV should be slightly below eye level when you are sitting in your preferred position.