Fitts's Law

What is Fitts's Law?

Fitts's Law describes how long it takes to move to a target. It goes back to psychologist Paul Fitts, who published it in 1954. The core idea: the time needed depends on two things, the distance to the target and the size of the target.

The relationship is logarithmic, not linear. Doubling a target's size helps noticeably, but the gains level off. For digital interfaces this means that how easy a button is to hit comes down to placement and area, not just color.

Why Fitts's Law matters

Every click and tap takes effort. Small or distant targets lead to misclicks, frustration and slower flows. On phones the effect is even stronger, because a fingertip is far less precise than a mouse pointer. Making key actions easy to reach removes friction exactly where revenue or activation is on the line.

How to use Fitts's Law in practice

• Enlarge hit areas: Make whole rows or cards clickable, not just a small icon or text link.
• Use proximity: Place the next action where the eye and pointer already are, such as the save button right below the form.
• Respect the thumb zone: On mobile, put frequent actions in the lower part of the screen.
• Use screen edges: On desktop the pointer stops at the edge, which makes targets there especially easy to hit.
• Keep risky actions apart: Do not place delete or cancel right next to the primary action.

Example

An online store shows a small "Add to cart" button at the top of the mobile product page, next to the image. Once shoppers scroll through the description, it is out of reach. A sticky, full-width button at the bottom of the screen fixes this. It is always visible, large enough and sits right under the thumb.