Interaction & Behavior

Fitts's Law

Time to reach a target depends on its size and distance.

Illustration for Fitts's Law

In practice

Takeaways

  • 1

    Primary actions should be large and easy to acquire.

  • 2

    Place frequent controls near the user’s likely focus area.

  • 3

    Separate destructive actions from primary ones.

Origins

Paul Fitts modeled human movement as a tradeoff between distance and target size. In digital interfaces, the same relationship applies to cursors, thumbs, and styluses.

Small or distant controls increase error rates and slow completion times, especially on touch devices.

Design Applications

  • Use at least 44px touch targets for key actions.
  • Keep primary buttons wide enough for confident tapping.
  • Put frequent actions in thumb-friendly zones on mobile.

Frequently Asked Questions

Further Reading