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Is there a known minimum physical size for reliable touch select triggers, considering only selection (no long-press or drag). From personal experience, I would guess it to be about 5x5 mm (0.2x0.2 inch). Is there a canonical answer?

Context: I want to make my chess-like game board have as many cells as possible, but I still want users to be comfortable selecting cells, as it will be a frequent action.

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1 Answer 1

up vote 16 down vote accepted

There's a comprehensive question on UX about touchscreen button sizes. The recommended size depends highly on your game, but the minimum size is quoted as 9-12mm, about half an inch, and this is based on the size of fingers.

Keep in mind that this is a guideline, and the cost of ignoring it is that your users will tap the wrong thing on occasion.

Depending on your game, you may need to go bigger - sometimes much bigger - than this minimum guideline. Here are some factors that will affect accuracy:

  • Do you need to tap quickly? Faster means less accurate
  • Will players use their thumbs? Less accurate
  • Is your demographic experienced gamers or younger? They may have above-average accuracy
  • Will your touch zones be right next to each other or have gaps in between? Gaps make it easier to use

You may also decide to accept a certain amount of input errors, as long as you make it easy for your players to correct themselves. Consider:

  • Allowing players to adjust their input after the initial tap
  • Add a "confirm" step
  • Add an "undo" function
  • Add clear feedback during the input to show what the game thinks the input will be
  • Reduce the impact of errors
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Thanks for comprehensive answer! –  Petr Abdulin Aug 5 at 8:15
3  
+1 Good answer, but I'd recommend against adding a confirmation step. User's tend to quickly click a button without thinking through the consequences. As a user, it's more friendly to provide an 'Undo' feature. –  FreeAsInBeer Aug 5 at 12:18

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