How to scale UI based off 1080p

I know how big I want the UI to be on 1920x1080 resolution so I want to set the UI to those sizes, and THEN convert to scale. I have a plugin that already changes from size to scale, but the problem is when I make the UI in studio the size I want on 1080p and set it to scale it actually ends up being the wrong size because the studio window is not 1080p. Hoping for a simple workaround here. I know one solution would probably be to find my studio resolution and do some maths and what not to figure out the sizes but that sounds like a super pain in the butt.