Fitts’s law (often cited as Fitts’ law) is a descriptive model of human movement primarily used in human–computer interaction and ergonomics. This scientific law predicts that the time required to rapidly move to a target area is a function of the ratio between the distance to the target and the width of the target.^[1] Fitts’s law is used to model the act of pointing, either by physically touching an object with a hand or finger, or virtually, by pointing to an object on acomputer monitor using a pointing device.

Fitts’s law has been shown to apply under a variety of conditions, with many different limbs (hands, feet,^[2] the lower lip,^[3] head-mounted sights,^[4] eye gaze^[5]), manipulanda (input devices), physical environments (including underwater), and user populations (young, old, special educational needs, and drugged participants).