For the best experience, please use a desktop or laptop computer. The test may not work properly on devices with small screens or touch input.

Fitts's Law

Fitts's Law is a fundamental principle in human-computer interaction (HCI) that describes the relationship between the time it takes to move and acquire a target, the distance to the target, and the size of the target itself. Developed by Paul Fitts in 1954, this law has become a cornerstone in the design of user interfaces, helping to optimize the layout and size of interactive elements such as buttons, menus, and icons. By understanding and applying Fitts's Law, designers can create interfaces that are more intuitive, efficient, and user-friendly, reducing the cognitive load and physical effort required for users to interact with digital systems. Whether you're a UX designer, developer, or simply someone interested in the science behind seamless user experiences, exploring Fitts's Law can provide invaluable insights into the intricate interplay between human behavior and technology.

Fitts's Law Equation

MT=a+b⋅ID=a+b⋅log⁡2(2DW)\mathrm{MT}=a+b \cdot \mathrm{ID}=a+b \cdot \log _2\left(\frac{2 D}{W}\right)
Symbol
Description
MTMT
The movement time, which is the time it takes to move from the starting position to the target.
aa
is the empirically determined constants for a particular pointing technique.
bb
is the empirically determined slope or rate of change for a particular pointing technique.
IDID
is based on the specific task (e.g., moving from one position to another).
DD
is the distance to the target.
WW
is the width of the target.
log(x)log(x)
determines the power value needed to raise 2 to equal xx.

Test instrauctions

The Fitts's Law test is designed to measure the time it takes to move from the center of the canvas to a target, based on the distance to the target and the size of the target. The test will be performed using both the primary and secondary hands, and the results will be recorded in a table for further analysis.

  1. Fill out the form on the right side with your personal information.
  2. Click the green start button to initiate the test. Start the test using your selected primary hand.
  3. Your task is to move the mouse cursor from the center of the canvas to the target as quickly and accurately as possible. (as shown in the animation below)
  4. The test will present targets of varying distances and sizes. It will measure the time it takes to reach the target, track any errors, and record the distance to the target as well as the size of the target.
  5. Each test iteration involves 3 different target sizes and 3 different distances, resulting in 9 combinations for the primary hand, and 9 for the secondary hand. (by default, the iteration is set to 8, resulting in 72 tests for the primary hand, and 72 for the secondary hand)
  6. Repeat the test multiple times until you receive a message instructing you to switch hands.
  7. Press the green button to continue the test with your second hand.
  8. Once both hands have been tested, you will receive a message indicating the end of the test.
  9. You can view the detailed results in the table below and download the data as a CSV file.
To begin the test, please fill out the form on the right side and click the green start button.
0
20 - 150
0 x 0
0

Test Settings

1745681918528

Results

IDinfo Age Gender PHinfo THinfo Device Iterationsinfo Directioninfo Timeinfo Widthinfo DTBinfo Distanceinfo Errorinfo
Test data will be displayed here.