Landscape rewrites reach and kills one-handed use
Aliases: landscape reach · two-handed grip · thumb arc
What it is
Turn the phone on its side and thumbs rest on the short edges, not on a bottom arc. Centre-screen becomes a stretch for both thumbs. A primary that was easy at the portrait bottom may now sit in a comfortable band, while Back at the top becomes remote. One-handed use almost disappears; the grip is two hands on the short sides. Landscape changes reach geometry. It is not the portrait canvas rotated 90 degrees.
A shopping app that lays its portrait tab bar on its side lets that bar eat the short height; content becomes a slit. Reach and visibility collapse together.
Why it happens
Grip follows the long axis. Portrait is often one hand cupping the bottom, thumb painting an arc. Landscape is often two hands on the short edges, thumbs at the bottom-left and bottom-right corners. Hot zones follow the thumbs; centre and top-mid go cold. Status plus nav also jump in share along the short axis, so visible height collapses. The portrait habit “primary at the bottom” may still be easy in landscape; “tools at the top” gets twice worse: farther, and crowding the short edge.
Video landscape exists for the picture. Tool-app landscape is often just the portrait shell rotated, hot zones never redrawn.
Studying it
Reach maps work: one-handed and two-handed landscape grips, tapping a 3×3 of targets; record success, time, grip changes. Independent variables: target location, device width, whether two hands are allowed. Dependent: hit rate, time from grip to tap, whether the device is passed to the other hand. Compare the same targets in portrait so you can say which locations went cold because of the rotation.
Lab grips are tidy. Side-lying on a sofa or a car mount will move the map again; extrapolate carefully.
Where it stops holding
Tablet landscape is often two-handed by default; one-handed was already weak. With a keyboard or trackpad, reach yields to a pointer. Game landscape has its own stick grip; do not audit it with a tool-app tab bar. If someone rotates only to glance at a keyboard or a photo, a full hot-zone redesign may be wasted — but the primary still must not land in the new cold zone.
Applying it
- Draw a landscape hot-zone map of its own: primaries near the two thumbs (short-edge ends), not top-dead-centre.
- Thin or stow the tall portrait bottom bar in landscape so short-edge height returns to content; park needed actions on the sides or in a layer.
- How to check: hold the real device in landscape, try one-handed once (usually fail), then walk the primary path two-handed. Any step that requires reaching from mid-short-edge to the top is cold. Move that control to a short-edge end a thumb can hit, and time the path again. Also measure content height: if the bar eats more than about a third of the short edge, cut the bar before talking hot zones.