To allow for finger size and parallax inaccuracy, for large and medium screen sizes, the dimensions of response areas on touch screens should be in the range between a minimum height and width of 10 mm (0.4 in.) and a maximum height and width of 40 mm (1.5 in.), with a separation distance of between 3 mm (0.1 in.) and 6 mm (0.25 in.).
Additional Information: The optimum touch-sensitive area depends on the application and required accuracy. Touch areas greater than 22 mm (0.9 in.) square do not tend to improve performance. 5908,100