Smartphone screens have been getting larger over time. Our design and implementation tools let us design the screens without having to know or design for the exact size. If the software, site, or app is designed well, what appears on the screen at any given time varies automatically according to the size of the screen.
What doesn’t vary automatically is the human hand and the human thumb. If you want to design a screen that’s easy and efficient to use, then you have to design for how people use their hands, fingers, and thumbs on a small to mid-size screen.
Myths Of One-Handed Use
Conventional wisdom holds that people mainly use their smartphones with one hand— that they hold the phone in their dominant hand and use the dominant thumb to tap and navigate. This does happen some of the time, but people also use the non-dominant hand some of the time, and sometimes they hold the phone in one hand and use the other hand for tapping.
You may have seen diagrams of a smartphone screen showing parts that are “natural” for the thumb to reach, parts that are a “stretch” for the thumb to reach, and parts that are marked “ow” for the thumb to reach. These are misleading since the thumb can’t stretch that far. It’s not that it hurts to reach further; it just doesn’t reach. When people can’t reach with their thumbs, they shift the position of the phone or use two hands.
Steven Hoober (2014) tested where 1,333 people tapped on a 5.1-inch screen smartphone. He found that:
- The center of the screen was the easiest to tap.
- The center of the screen was the most accurate and fastest target.
- People often shifted the way they were holding the phone to touch everywhere else on the screen.
- Most taps outside the central area involved two hands.
- People held their phones with one hand when they were looking at the phone or carrying it around, but they sometimes switched to two-handed use when they were actively interacting.
- People held the phone and used the thumb of that same hand for interactions 49 percent of the time.
- People frequently cradled the phone with one hand and used their index finger of the other.
To complicate matters further, the size and reach of people’s thumbs vary widely.
The “Top-Left” Standard Must Go
Since people are using their thumbs a lot and since the thumb doesn’t easily reach the top left of the smartphone screen, it makes sense to not use the top left as a place for any important controls. Although using the top left, especially to display the “menu” icon, seems to be a standard at the moment, it’s one of the worst places to put a frequently used control and will, most of the time, require a two-hand shift. It’s better to put important controls in the center or on the bottom of the screen.
Takeaways
- When you design for smartphone screens, keep the most important controls away from the edges of the screen. Stay in the middle of the screen as much as possible.
- Consider not using the top left area of the screen for the control that drops down the menu.
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