Usability Glossary: Fitts' Law

T = k log₂(D/S + 0.5), k ~ 100 msec.

T = time to move the hand to a target
D = distance between hand and target
S = size of target

Fitts' Law is a model to account for the time it takes to point at something, based on the size and distance of the target object. Fitts' Law and variations of it are used to model the time it takes to use a mouse and other input devices to click on objects on a screen.

Broadly, Fitts' Law can be applied by designers to suggest moving target buttons closer and making them larger for extremely commonly used buttons. In detail, applying the formula can be extremely useful for exact design of time-critical applications.

see also

cognitive modeling

GOMS

Hick's Law

input device

Meyer's Law

power law of practice

categories

Glossary Categories > I/O Devices > I/O Design Principles

Glossary Categories > Psychology > Cognitive Modeling

Glossary Categories > Usability Methods > Cognitive Modeling

Glossary Categories > Design Principles > I/O Design Principles