[header] How to choose an hdtv [title] Measure the available area. [step] If you are putting an hdtv in an existing home theater cabinet, make sure you know the maximum size that will fit. Measure the tv enclosure diagonally, as this is how hdtvs are measured. 
For example, a 50 " hdtv is 50 " from corner to corner, but is less than that horizontally. [title] Measure the distance from the couch to the tv.