title: Aspect ratio
text: The aspect ratio of a geometric shape is the ratio of its sizes in different dimensions. For example, the aspect ratio of a rectangle is the ratio of its longer side to its shorter side—the ratio of width to height, when the rectangle is oriented as a "landscape".
  
  The aspect ratio is most often expressed as two integer numbers separated by a colon (x:y), less commonly as a simple or decimal fraction. The values x and y do not represent actual widths and heights but, rather, the proportion between width and height. As an example, 8:5, 16:10, 1.6:1,  and 1.6 are all ways of representing the same aspect ratio.
  
  In objects of more than two dimensions, such as hyperrectangles, the aspect ratio can still be defined as the ratio of the longest side to the shortest side.
  
  Applications and uses
  The term is most commonly used with reference to:
   Graphic / image
   Image aspect ratio
   Display aspect ratio
   Paper size
   Standard photographic print sizes
   Motion picture film formats
   Standard ad size
   Pixel aspect ratio
   Photolithography: the aspect ratio of an etched, or deposited structure is the ratio of the height of its vertical side wall to its width.
   HARMST High Aspect Ratios allow the construction of tall microstructures without slant
   Tire code
   Tire sizing
   Turbocharger impeller sizing
   Wing aspect ratio of an aircraft or bird
   Astigmatism of an optical lens
   Nanorod dimensions
   Shape factor (image analysis and microscopy)
   Finite Element Analysis
  
  Aspect ratios of simple shapes
  
  Rectangles
  
  For a rectangle, the aspect ratio denotes the ratio of the width to the height of the rectangle. A square has the smallest possible aspect ratio of 1:1.
  
  Examples:
   4:3 = 1.: Some (not all) 20th century computer monitors (VGA, XGA, etc.), standard-definition television
   : international paper sizes (ISO 216)
   3:2 = 1.5: 35mm still camera film, iPhone (until iPhone 5) displays
   16:10 = 1.6: commonly used widescreen computer displays (WXGA)
   Φ:1 = 1.618...: golden ratio, close to 16:10
   5:3 = 1.: super 16 mm,  a standard film gauge in many European countries
   16:9 = 1.: widescreen TV and most laptops
   2:1 = 2: dominoes
   64:27 = 2.: ultra-widescreen, 21:9
   32:9 = 3.: super ultra-widescreen
  
  Ellipses
  For an ellipse, the aspect ratio denotes the ratio of the major axis to the minor axis. An ellipse with an aspect ratio of 1:1 is a circle.
  
  Aspect ratios of general shapes
  In geometry, there are several alternative definitions to aspect ratios of general compact sets in a d-dimensional space:
   The diameter-width aspect ratio (DWAR) of a compact set is the ratio of its diameter to its width. A circle has the minimal DWAR which is 1. A square has a DWAR of .
   The cube-volume aspect ratio (CVAR) of a compact set is the d-th root of the ratio of the d-volume of the smallest enclosing axes-parallel d-cube, to the set's own d-volume. A square has the minimal CVAR which is 1. A circle has a CVAR of . An axis-parallel rectangle of width W and height H, where W>H, has a CVAR of .
  
  If the dimension d is fixed, then all reasonable definitions of aspect ratio are equivalent to within constant factors.
  
  Notations
  Aspect ratios are mathematically expressed as x:y (pronounced "x-to-y").
  
  Cinematographic aspect ratios are usually denoted as a (rounded) decimal multiple of width vs unit height, while photographic and videographic aspect ratios are usually defined and denoted by whole number ratios of width to height. In digital images there is a subtle distinction between the display aspect ratio (the image as displayed) and the storage aspect ratio (the ratio of pixel dimensions); see Distinctions.
  
  See also
   Axial ratio
   Ratio
   Equidimensional ratios in 3D
   List of film formats
   Squeeze mapping
   Scale (ratio)
   Vertical orientation
  
  References
  
  Ratios