The viewing angle of an LCD panel is generally expressed for both horizontal and vertical in degrees from perpendicular to the display or as a total of left & right and up & down. So for example the newer IPS panels now claim up to 178 degree viewing angle.
A few important points to note with viewing angle:
- As I am likely to mention for other specifications it is difficult to choose a panel solely on specification, it is worth seeing the panel. I have seen a panel with excellent viewing angle ratings but when testing it I found a color shift at around 45 degrees from perpendicular.
- Specifications are generally expressed for the panel in landscape orientation so if the panel is going to be used in portrait mode the up/down viewing angle in the specification will be very relevant.
- TN type TFT panels may only offer a viewing angle of 130 degrees with different up/down results making them unsuitable for portrait mode.
Overall viewing angle is becoming less of an issue as there are panel choices to meet the requirements of most users.