The code is in main.py and the .exe is in the dist directory.
This calculator allows you to choose between 512x512 for stable diffusion and 1024x1024 for stable diffusion xl. For the best quality in your generation it's recommended that you keep the same pixel count when changing the aspect ratio to something besides 1:1 If you want a 16:9 aspect ratio for example on sd, select the 512x512, enter 16 in the first field, and 9 in the second field. It will output the result at the bottom, in this case a resolution that keeps the same pixel count as a 1:1 512x512 image but in 16:9 equals 682x383.