Display resolutions maths - calculator and tables (dotforward.de)

Sample computation:

Input:

  Diagonal: 14.1 inch 
  Resolution: 1024 × 768 pixels

Output:

  Diagonal: 35.8 cm 
  Size: 28.7 × 21.5 cm, 0.8 Megapixels 
  Resolution: 90.8 dpi 
  Pixel pitch: 0.280 mm 
  Aspect ratio: 4:3 
  Viewing distance: 50 - 70 cm