The 50-millisecond budget
Carleton University research shows visual judgments form in 50 milliseconds. Above the fold has roughly that long to communicate three things: what this is, who it's for, and what to do next. Pages that try to do more (multiple CTAs, animated background, rotating headlines) usually communicate less.
The five-element rule
Headline, subheadline, primary CTA, trust signal, supporting visual. Five elements is the upper bound — fewer is fine, more usually hurts. Pages we've analyzed that hit all five and nothing else score in the top quartile of First Impression. Pages that add a video player, a chat widget, a notification bar, and a logo bar score in the bottom third.
Mobile changes the math
"Above the fold" on mobile is roughly 320–600 pixels — far less than desktop. The visual usually has to move below the headline, the subheadline gets shorter, and the trust signal often becomes a single number rather than a logo bar. Design for mobile first, then expand the hero for desktop. Check your above-the-fold to see what visitors actually see.