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.
As an example, 8:5, 16:10, 1.6:1, 8⁄5 and 1.6 are all ways of representing the same aspect ratio.
In geometry, there are several alternative definitions to aspect ratios of general compact sets in a d-dimensional space:[3] If the dimension d is fixed, then all reasonable definitions of aspect ratio are equivalent to within constant factors.
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.