Level: Intermediate
Fitts's Law states that the time to reach a target depends on its size and distance, a decades-old principle that directly informs how buttons and links should be sized and placed.
Bigger, Closer Targets Are Faster to Hit
A primary call-to-action button benefits from being large and positioned where a visitor's attention and cursor or thumb are already likely to be.
This Matters Even More on Touchscreens
Imprecise touch input makes target size and placement even more consequential on mobile than with a precise mouse cursor.
Don't Apply This Principle at the Expense of Everything Else
Making every element large defeats the purpose of hierarchy; Fitts's Law should inform your most important targets specifically, not the entire page uniformly.
Next step: Use the Webpage Screen Resolution Simulator to check how your primary buttons and targets actually size and position across different screen dimensions.