I created this 200x200px box in AI file (72ppi):
After saving it as PDF, the PDF opens in different resolutions on different apps.
Here it opens as 305x305px in Adobe Reader:
Here it opens as 268x268px in Google Chrome:
What’s happening here?
I wanted to do a web presentation in the popular 1920x1080px, but I noticed, that the 100% didn’t fit the 1920x1080px screen in any application.
EDIT: I used LightShot printscreening tool to estimate the dimensions of the box.
What you see are the effects of the default resolution of the various PDF viewers. It used to be an idea to have the “real” view on screen (in other words, something appearing as 1 inch on paper should also be 1 inch on screen).
In Acrobat, you can set that resolution in the preferences.