Have you ever been browsing a web site on your smart phone or tablet and found that on some sites, the links are so tiny and so tightly packed, that it’s near impossible to click the right one?
I have definitely been there and it’s equally frustrating each time. As the use of smart phones and tablets increases, so does the importance of having big enough target areas to interact with. But it’s not only important for mobile browsing. The truth is that it benefits desktop users as well.
Fitts’s Law is a classic rule of thumb in Usability. The law can be expressed in a fairly complex mathematical way but in a nutshell it states that the larger and closer a target is, the easier and faster it is to click it.
It’s not exactly Rocket Science, but still it highlights the importance of having, not only big enough targets, but also to position them intelligently.
If you want to know more about Fitts’s Law there’s an excellent explanation over at Particle Tree.
Designing for Touch
For touch devices, such as smart phones and tablets, a big enough touch target is even more important than on desktop. While a mouse pointer is a precision instrument with a click area of just 1 x 1 pixel, a human finger is more of a sledge hammer. The avarage size of the pad of a human index finger is 1.6 to 2 cm which translates to about 45-57 pixels on a screen.
You’ve probably experienced the frustration yourself when trying to click small links that are tightly packed on a smart phone. It can be really hard to hit the right target and that’s not the experience you want people to have with your web site.
Recommended touch target sizes
Apple iOS Human Interface Guidelines state that a touch target should be at least 44 x 44 points large. (The reason they’re using points instead of pixels is that points can be used for both standard and retina displays).
Microsoft’s Windows Phone UI Design and Interaction Guide suggest that the size of the touch target should be 34 pixels with an absolute minimum of 26 pixels and Nokia’s Developer Guidelines state that the touch target should be at least 1 x 1 cm.
I actually I think that Nokia has the best guidelines since it states its minimum dimensions in cm. I mean 44 pixels can be very different on different screens and devices.
What you don’t have in size you can make up in space
Another interesting aspect of this is that if you absolutely do need to have relatively small touch targets you can partly compensate that by increasing the space between the targets. By doing that you limit the chance of missed targets.
The rule is: The smaller the target, the bigger the gap.
Enough already, I think you get why it’s important to have big enough click/touch targets. The question is, how is it done in practice?
The first thing to recognize is that the clickable area could be well outside the visible area of the object.
For links in a list, the easiest way is to increase the padding. Instead of having a padding on the list-item you should have it on the link itself. In this example I simply add a 10 pixel padding to a link. Watch how that dramatically increases its clickable area (The faint red background indicates the clickable area).
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Checkboxes and Radiobuttons
For checkboxes and radiobuttons, which often are really small, the trick is to put them inside a label and add a generous padding to them. By connecting the checkbox and the label via the
id and the
for attributes, the entire area of the label toggles the checkbox.
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In this case the padded click area is over 50 times larger than the checkbox.
Of course there are other elements that this could be applied to as well but these two examples should be enough to give you an idea of how to go about it.