Orientation and Screen Sizes

Maria is booking a hotel for a weekend in Porto on the train. She fills in her name, email and the guests, then turns the phone sideways to watch the hotel’s video tour. The video starts from the beginning. She turns the phone back to finish the booking. The form is empty. She sighs, closes the app and books on a competitor’s site instead.

Nobody on the team had rotated the phone in the middle of the form. On their test devices the screen looked fine in both orientations. It just forgot everything in between.

Why it matters

Users rotate their phones all the time: to watch a video, to see a wide photo, to type on a bigger keyboard, or simply because they put the phone down on a table. They also use many different screens: a small iPhone SE, a huge Pro Max, an iPad, a foldable that turns from phone to tablet mid-session, or a split screen next to another app.

Every one of these changes the space the app has. Two kinds of bugs appear:

• Layout bugs: content hidden behind the notch or home indicator, buttons pushed off screen, text stretched into unreadable lines, dialogs cut off.
• State bugs: on Android, rotation re-creates the screen. Anything the app didn’t save (a half-filled form, a scroll position, a playing video) is gone. This is a classic state persistenceState persistenceWhether the app remembers what the user did after navigating away, rotating, or restarting.Open in glossary → bug.

Portrait, landscape and rotation lock

OrientationOrientationWhether the device is held upright (portrait) or sideways (landscape).Open in glossary → is simply how the user holds the device: portrait (upright) or landscape (sideways). What the app does about it depends on three settings:

What happens when the phone rotates

The platforms handle rotation very differently, and that difference explains most rotation bugs.

Safe areas: the parts of the screen you can’t fully use

Modern screens aren’t simple rectangles. They have rounded corners, a notch or Dynamic Island for the cameras, a home indicator at the bottom, and system bars. The safe areaSafe areaThe part of the screen not covered by the notch, Dynamic Island, rounded corners or home indicator.Open in glossary → is the rectangle where content won’t be covered or clipped. Backgrounds and images can extend beyond it, but text and buttons should stay inside.

Notice that in landscape the iPhone’s island is on one side, yet iOS insets both sides, so content stays centered whichever way the phone is turned.

Points, pixels and dp

Screens have very different pixel densities, so apps don’t measure in pixels. They use logical units that look roughly the same size on every screen:

For testers this matters because requirements, designs and bug reports speak in logical units. “The button is 40 pt tall” is a fact you can check against the 44 × 44 pt minimum touch targetTouch targetThe area of the screen that responds to a tap, which should be large enough for a finger.Open in glossary →; “the button is 120 px tall” means nothing until you know the density.

Users can also change the logical size: Display Zoom on iPhone (Settings › Display & Brightness › Display Zoom › Larger Text) makes a big iPhone behave like a smaller one, and Display size on Android (Settings › Display) changes the dp width of the screen. Together with font size (Dynamic TypeDynamic TypeThe phone setting that lets users make text bigger or smaller across apps.Open in glossary → on iOS), these are some of the most common sources of cut-off text.

Tablets, foldables and split screen

• Tablets have room for more: two panes (list + detail), sidebars, grids. A stretched phone layout on a tablet is a usability bug.
• Foldables change size while the app is running. A Galaxy Z Fold goes from a tall, narrow cover screen to an almost square inner screen. Flip-style phones have a tiny cover screen. The app must keep its state and switch layout, and avoid putting buttons right on the hinge.
• Split screen and windows. On iPad (Split View and Slide Over on older versions, Stage Manager, and the freely resizable, tileable windows of iPadOS 26) and Android (split screen, free-form windows on tablets), the app gets only part of the screen. A tablet app in a 50/50 split is suddenly phone-sized.

Android groups widths into window size classes: compact (under 600 dp: phones in portrait), medium (600–839 dp: tablets in portrait, unfolded foldables) and expanded (840 dp and up: tablets in landscape; newer guidance splits very wide windows further into large, from 1200 dp, and extra-large, from 1600 dp). Heights under 480 dp are compact (phones in landscape). These are good test buckets.

Try it: the device simulator

Switch devices, rotate, fold and turn the safe-area overlay on. Then switch off App respects safe areas to see what a careless app looks like, and add a few pizzas to the basket before you rotate: the basket should survive everything.

The keyboard and video in landscape

Two features get very tight in landscape:

• The keyboard. In landscape the on-screen keyboard can cover more than half of the screen. The focused field must stay visible, dialogs must move up or scroll, and the action button (Send, Apply, Log in) must be reachable. Some Android keyboards switch to a full-screen editing mode in landscape, which hides your app entirely while typing.
• Video. Users expect a playing video to go full screen when they rotate to landscape and return when they rotate back, without restarting and without losing the playback position, subtitles or quality setting. Picture-in-picture and AirPlay/Cast add more transitions to try.

What to test

Rotation and state

• Rotate on every screen with input, scroll position, selection, a playing video, an open dialog or menu, and during loading.
• Rotate several times quickly, and rotate while a network request is running (is it sent twice?).
• Change other configurations too: fold/unfold, split screen, dark mode, font size. See also Background and Foreground.

Layout

• Nothing important under the notch, Dynamic Island, camera hole, rounded corners or home indicator, in both landscape directions.
• Landscape uses the extra width sensibly; text lines stay readable (roughly 45–75 characters).
• Smallest supported phone, largest phone, tablet, foldable (folded and unfolded), split screen.
• Largest font size and Display Zoom / Display size, which together shrink the available space a lot.

Keyboard, dialogs and media

• With the keyboard open in landscape, the focused field and its buttons are visible or reachable by scrolling.
• Videos go full screen and keep playing across rotation.

Locked orientation

• With rotation lock on, rotating does nothing. In portrait-only apps, check that rotation can’t sneak in (for example through a video player or a web view).

Common bugs

Find the bug

This hotel booking screen supports both orientations, and it has six orientation bugs. Use the Rotate phone button below the device. Before each rotation, change something: type in the form, scroll, play the video, open the promo code dialog.

Tools and how-to

# Lock rotation and force landscape (0 = portrait, 1 = landscape, 3 = reverse landscape)
adb shell settings put system accelerometer_rotation 0
adb shell settings put system user_rotation 1

# Pretend to be a smaller or denser screen, then reset
adb shell wm size 1080x1920
adb shell wm density 480
adb shell wm size reset
adb shell wm density reset

Example test cases

Checklist

Check your understanding

Related: Gestures · Device Fragmentation · Simulators and Emulators · adb Basics