Put a dot (a simple sticker or piece of tape will do the trick) in the center of the top 2/3rds of your computer screen. Now, adjust your desk and chair until your eyes are in an exact perpendicular line with this dot.

The same idea holds true if you prefer a standing desk. Add the dot to your screen and adjust your desk height, while standing in comfortable shoes, until your eyes are in the appropriate line of sight.

The Easiest Way to Figure Out the Perfect Desk Office Chair Height – Apartment Therapy

Via Lifehacker UK.

I won't be doing this. I don't fancy marking my gorgeous 27in iMac screen with a dot and I can't pop some paper Post-It Note on it because I have papyrophobia.

But I like the concept and will be squinting at my iMac to guess it because my office chair is the most gorgeous thing except for how it sinks during the day.