Fitts’s Law

What is Fitts’s Law?

Fitts’s Law is a classical principle in psychology and interaction design, particularly important in the field of UX/UI. Proposed by Paul Fitts in 1954, this law describes the relationship between target size, distance to the target, and time required to interact with that target. Simply put: the larger and closer the target, the easier and faster it is for users to click on it.

Basically, Fitts’s Law states that:

The time for users to move the cursor to a target depends on the size of the target and the distance from the starting point to that target.

In UX/UI design, this translates into principles such as:

• Increase the size of important buttons or links.

• Place frequently used actions in easily accessible locations.

• Reduce the distance between consecutive actions.

Real-world examples:

• The “Submit” button in a form: If the button is too small or far from the area where users just input information, they will take extra time to click on it. A good design will make the button large enough, with good contrast and placed near the last input field.

• Screen corners or edges: According to Fitts’s law, screen corners are “sweet spots” because the cursor will be “caught” there – you cannot go further. Therefore, many operating systems (such as macOS) place the Apple menu or close button in the upper left corner for easy access.

Application in UX/UI design:

According to Nielsen Norman Group, applying Fitts’s Law helps you:

• Design interactive behaviors more effectively.

• Optimize user interaction flows.

• Increase task completion speed and reduce errors.

In Material Design or Apple HIG, you will see specific recommendations for the minimum sizes of buttons (typically at least 44x44pt or 48x48dp) – which is partly based on the principles of Fitts’s Law.