If no one is going to say the obvious answer, I will:

You sit further away from your screen (relative to your screen size), than the average user. Let’s work backwards:

Assume you use 150% zoom on average. And you sit 100cm from computer screen. Then I predict an average user would sit 100cm/1.5 =about 66cm from same screen.

edit: or a screen with the same PPI or pixel density