How do I check 16:9 vs 19:9.5 vs 4x3, tablet vs phone?

I have an app with a few different layouts to cater to aspect ratios.

In the loader event sheet I need to detect the ratio. PlatformInfo.WindowInnerHeight might be the best option.

Will this work? Or is there a better option?

Also, what if ratio does not fit any as described?

Also, the 16:9 and 19.5:9 are portrait and the 4X3 is landscape. Will this influence the equations?

Don't design for specific aspect ratios. Design for all of them. construct.net/en/tutorials/supporting-multiple-screen-17

Either design for the narrowist width and have your layouts wide enough to cover the widest width, or design for the widest width with the assumption that the ends can get cut off for the squarest aspecct ratios.

Thank you for the suggestion:) My app is not a traditional game and has many different elements. A 4:3 model is significantly different than a 19.5:9 thus the need variations.

Do you have any suggestions as how to detect the aspect ratio?