A common challenge that we all face, especially with the trend of making bigger phones, is reaching widgets far away from our thumbs reach, on our phones screens while holding them. Designers try to optimize that by placing most frequently accessed buttons in the most comfortable reach for the thumb (by using heat maps from test sessions or from live products). A recent paper proposes a model for calculating the thumb functional area[1]. By giving the algorithm four values, it calculates the area and plots it. The four values are:
- Finger Span or Hand size (s): the distance between the thumb and index finger as shown in the figure
- Index-finger distance (d): the distance of the index fingertip from the point of intersection of the hand with the phone
- Hand orientation
- Hand position from origin
Engineering The Design 