Fitts' Law Calc

Fitts' Law Calculator | UX Design Tool

Fitts' Law Calculator

Calculate target acquisition time based on distance and width

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About Fitts' Law

Fitts' Law is a predictive model of human movement primarily used in human-computer interaction and ergonomics. It predicts the time required to rapidly move to a target area, such as clicking a button or selecting an item from a menu.

Key Principles:

  • Movement time increases with distance to the target
  • Movement time decreases with target size
  • The relationship is logarithmic, not linear

Applications in UX Design:

  • Button and interactive element sizing
  • Menu and navigation layout optimization
  • Touch target sizing for mobile interfaces
  • Input device comparison and evaluation

Typical Values:

Device a (intercept) b (slope)
Mouse 0.083 0.127
Trackpad 0.120 0.180
Touchscreen 0.150 0.250

Fitts' Law Calculator - Free tool for UX designers and researchers