Have you ever used a touch screen phone or mobile device and find yourself frustrated because of small UI touch elements that can’t be selected with ease? What about two completely different options that are too close to each other and instead of renaming  a file you accidentally delete it? That’s because there’s not a standard for how touch user interfaces should be made. Of course different manufacturers have their own guidelines, but there’s no universal rule and this has one big effect on consumers: usability sucks for most modern smartphones. Apple seems to be the one that gets it right most of the times, but there’s room for improvement everywhere.

    Today a friend recommended me an interesting article to read: Touch Target Sizes, which presents how different manufacturers see this problem and their guidelines. I’m going to tell you in short the differences. If you want to help the guy who wrote the article you could send him specs for the manufacturers he didn’t include in the article.  So, let’s see why there’s such a mess with touch UIs these days:

    • Apple - elements should be 29 x 44 pixels minimum, that’s for their 164 ppi (pixels per inch) screen of the iPhone
    • Microsoft - 9mm/34px x 7mm/26px minimum touch size and at least 2mm/8px between elements. Microsoft reckons that more important elements could be made bigger
    • Nokia - the smallest possible element should be bigger than the smallest average finger pad (that’s a wise choice), which means 0.4 inch/1cm in diagonal or a 1cm x 1cm square
    • Ubuntu - they take into consideration the size of an adult finger which is 16 – 20 mm wide and say people usually use the finger pad, not tip, which is about 10 to 14 mm wide. The conclusion they draw is that an element you can interact with should be bigger than 1cm (0.4 inch)

    So there you have it: anything smaller than 1 x 1cm (0.4 x 0.4 inch) will be hard to reach and interact with. Now when you’ll miss the icon of an app on your smartphone you’ll know why!

    Touch UI elements size guideline

    Touch UI elements size guideline