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Human Standards

Anthropometrics (Reach, Size Ranges)

People come in all shapes and sizes — and so do their hands, their reach, and the devices they use. A button that’s perfectly placed for one user might be impossible to reach for another.

Why this matters

Section titled “Why this matters”

Body dimensions vary dramatically across populations. Hand breadth alone ranges from about 70–100 mm in adults, and thumb length from 45–75 mm. When you’re designing touch targets or placing critical buttons, these differences can make or break the experience.

The thumb zone

Section titled “The thumb zone”

On mobile, most people hold their phone with one hand and navigate with their thumb. This creates predictable “reach zones”:

  • Easy zone (lower center): About 60 mm from the thumb anchor. Put your most-used actions here.
  • Stretch zone (middle, opposite side): Reachable with some effort. Fine for less frequent actions.
  • Hard zone (top corners, far edges): Requires grip shifts or two hands. Avoid placing critical controls here.

Device diversity

Section titled “Device diversity”

Screen sizes now range from 4” phones to 7”+ phablets to 13” tablets. What works on one won’t work on all.

  • Heavier devices (over ~200g) cause fatigue during extended one-handed use.
  • People hold phones differently: cradled, two-thumb, index-finger pointer. Your design should accommodate multiple grips.

Designing for everyone

Section titled “Designing for everyone”
  • Offer UI density settings — let users choose compact or spacious layouts.
  • Support one-handed modes or reachability features for large screens.
  • Allow key controls (like floating action buttons) to be repositioned.
  • Test with users across the physical spectrum, including those with limited dexterity.

References

Section titled “References”
Maintained by AK Lodhi