64 × 16 px
movement time
reaction time
time of processing one bit
by human nervous system
difficulty of the various
combinations of D and W
distance to target
target width
250 ms — cursor hover
570 ms — hover and click

ms

ms

ms


px
2 •

px
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Choose image of interest

it won't be uploaded to server
Fitts' law measures cursor travel time to target
and shows what size it must be.
Move       to cursor strat position and over the target.
Measure time
100%