I frequently need to calculate aspect ratios and dimensions when resizing images, so I wrote a ratio calculator plugin for Alfred to make the calculation as efficient as possible.
It works by reading a simplified ratio equation syntax in the form of a b c d where a, b, c, and d represent the numerators and denominators in an a/b=c/d ratio equation. Any non-number can be used to represent the missing number.
E.g., 2/4=x/10 would be typed as 2 4 x 10 and Alfred will return 5, ready to be copied to the clipboard.
Installation instructions and source on GitHub
Download Ratio Calculator.alfredworkflow