Follow these guidelines for designing touch-based interactions on mobile and tablet devices to increase application usability and user enjoyment.
So how big should you make the touch targets on a touch UI?
The MIT Touch Lab study of āHuman Fingertips to Investigate the Mechanics of Tactile Senseā found that the average human finger pad is 10ā14mm and the average fingertip is 8ā10mm.
That means the magic number is 10mm.
Most users can comfortably and reliably hit a 10mm by 10mm touch target. Different mobile platforms express this size recommendation differently, however.
For example, in the iPhone Human Interface Guidelines, Apple recommends a minimum target size of 44 pixels by 44 pixels (88px on retina display) or about 8mm round. Since physical pixel size can vary by screen density, Appleās pixel specifications apply best to the iPhoneās 320 by 480 pixel, 3.5-inch display (164ppi). Since the release of the iPhone 4ās retina display (326ppi), Apple has updated these specs to points instead of pixels.
In the āWindows Phone UI Design and Interaction Guide,ā Microsoft suggests a recommended touch target size of 9mm/34px, and a minimum touch target size of 7mm/26px. Since different phone platforms will have different guidelines, itās best to check with the platformās specifications and design accordingly. However, regardless of platform, a minimum touch target of 10mm x 10mm is a good estimate/rule of thumb to apply to all your touchscreen designs (see Figure 8.5). For desktop designers, this will feel ridiculously largeātoy-like even! But have faith, itās important to make touch targets easy for users to engage with.