4 Tips for Designing the Most Effective Touchscreen Interface

Size: For reliable activation size all trigger elements with large fingers in mind. Make sure that these elements are big enough to easily touch (but not so big that they get pressed accidently). To further reduce touch errors, the minimum height and width of each activation area should be equal to the measurement of the average fingertip size, which is 8 to 10 mm (0.3 to 0.4 in.).

Spacing: Space elements far enough apart to avoid them accidentally being pressed. There should be at least 1 to 2 mm (0.04 to 0.08 in.) of space between each element. 

Make critical elements larger: Errors tend to increase as touch areas get smaller, so don't use undersized buttons for important trigger elements. Whenever possible, enlarge these buttons and try to make them much bigger than other nearby elements. In general, when designing trigger elements, “bigger is better” for both sizing and spacing.

Keep it simple: Keep messaging clear, concise, and simple, and only elaborate when absolutely necessary. Also, before adding any new items, ask the question, “Does the user really need to see this?” Think like a minimalist and only show those items that are needed for each task.

Be intuitive and consistent: Your users are probably well acquainted with many other interfaces that they frequently use. Help users feel more comfortable by creating layouts that are similar to the interfaces with which they are already familiar. Be consistent and use the exact same language, layout, and labeling terms throughout all menu options.

Remember that hands get in the way: Hands can cover important information when pressing trigger elements. Best practice is to position the labeling information on or above these elements (and not underneath them) so that information doesn’t get covered by the hands. Also, since most users are right-handed, consider placing information on the left side (so users can still read it while touching the buttons).

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Provide feedback: Provide immediate feedback using auditory and visual cues or simple messaging to show when a user’s actions are right or wrong. If the user causes an error, use messaging as a teachable lesson to clearly explain the problem (and to help prevent it from happening again).

Choose the best activation method: “Up triggering” (activation upon release) is preferred over “down triggering” (activation upon press) to reduce errors. Best practice is to highlight the element when first touched and then trigger the element when the finger is released.