Work out screen size converter instantly with clear inputs, formula shown and shareable results.
Screens are sold by diagonal, which hides how much area you actually get. Splitting the diagonal by the aspect ratio gives width and height: a 27 inch 16:9 panel is 59.8 by 33.6 cm. Aspect ratio matters enormously - a 27 inch 16:9 screen has 11% less area than a 27 inch 4:3 one.
Width and height
width = diagonal x aw / sqrt(aw^2 + ah^2), similarly for height
Area
area = width x height
Because a squarer rectangle encloses more area for a given diagonal. The square is the extreme case.
Usually yes for modern panels, but older CRTs quoted tube size including the bezel-hidden margin.