Black bars around your apps are annoying. They waste screen space and make everything look smaller than it should. Your Android phone has a perfectly good display, but for some reason, certain apps just won’t stretch to fill it.
This happens all the time. System updates change settings without asking. Apps get stuck using old screen dimensions. Sometimes your phone’s display options are just set wrong. Whatever the reason, you can fix it yourself in about five minutes.
Why Your Apps Won’t Fill The Screen
Your Android display has specific measurements. Apps are built to fit certain screen shapes. When these don’t match up, you get gaps.
Here’s what’s actually going on. Older phones had squarer screens, usually in a 16:9 ratio. Newer Android phones are taller and narrower, with ratios like 18:9, 19:9, or even 21:9. Apps made before these taller screens existed don’t always know how to handle them. Your phone plays it safe by adding black bars instead of stretching the app in weird ways that might cut off buttons or text.
Android has settings that control how apps display. These can force apps to use your full screen even when they don’t want to. But these settings aren’t always turned on. Sometimes they’re off by default. Other times, a system update resets them.
Your phone might also be running apps in compatibility mode without telling you. This happens when Android thinks an app is too old for your screen. It displays the app the way it would have looked on an older phone. You stay safe from crashes and glitches, but you also get those ugly borders.
App Not Full Screen (Android): Common Causes
A few specific problems cause most full screen issues. Let’s break down what’s actually happening.
1. Full Screen Display Settings Are Off
Android lets you force apps to use your entire screen. This setting exists in your display options. It’s often turned off for certain apps without any clear reason why.
Most people never find this setting because they don’t know to look for it. Your phone doesn’t enable full screen mode automatically for every app. Some get it, some don’t. There’s no logic to it.
System updates make this worse. When Android updates, it sometimes wipes your custom display settings and goes back to defaults. An app that was working fine yesterday suddenly has black bars today.
2. The App Is Outdated
Developers have to update their apps for new screen sizes. Apps that haven’t been updated in months or years don’t recognize your display properly. They were coded for old screen shapes and that’s all they know.
You can spot this easily. Open an app that gets regular updates and it fills your screen perfectly. Open an old, abandoned app and it sits in a tiny box. The difference is obvious.
3. Your Screen Resolution Is Too Low
You can lower your screen resolution to save battery. Sounds good, right? But when you do this, some apps think your screen is physically smaller than it actually is. They shrink themselves to match the lower resolution.
The app reads your current resolution setting and adjusts its display area. It renders itself for a smaller screen size, then shows that smaller version on your full display. That’s where the gaps come from.
4. Display Size Is Set Wrong
Android lets you make everything bigger or smaller through display size settings. This is separate from resolution. Display size changes how large your icons and text appear.
Apps use these settings to figure out how much space they should take up. Set your display size too large and some apps think they need to show less content. They shrink their active area. Set it too small and apps get confused trying to fit everything in. Either way, you end up with wasted screen space.
5. Developer Options Are Messing Things Up
Developer options are hidden settings meant for people who build apps. If you’ve turned these on, you might have changed something that affects how apps display. Settings like “smallest width” or “force activities to be resizable” can stop apps from expanding.
These aren’t meant for regular use. But once developer mode is on, it stays on. Your phone won’t warn you that a developer setting is causing problems. You just see apps that won’t fill your screen and wonder why.
App Not Full Screen (Android): DIY Fixes
You can fix this yourself. Here’s how to do it, starting with the easiest methods.
1. Turn On Full Screen Mode
Open Settings and find Display. The exact name depends on your phone, but it’s usually called Display or Display & Brightness. Look for an option labeled Full Screen Apps, Full Screen Display, or App Aspect Ratio.
Tap it. You’ll see every app on your phone listed. Each one has a toggle or menu next to it. Find the app that’s giving you trouble and make sure it’s set to Full Screen or Auto. If it says Original or the toggle is off, switch it.
Go back to your home screen and open the app. It should fill your display now. Check your other apps too while you’re at it. You might find several that aren’t set to full screen.
2. Update The App
Open the Google Play Store. Tap your profile icon at the top right corner. Select “Manage apps & device” from the menu that appears.
Look at the section showing apps with available updates. Find your problem app and tap Update. Can’t find it in the list? Search for the app directly in the Play Store and check its page for an update button. Install any available update, then open the app to see if it fills your screen properly now.
3. Set Your Resolution To Maximum
Go to Settings and open Display. Find Screen Resolution or Display Resolution. It might have a slightly different name on your phone, but it’s usually near the top of the display menu.
Tap it and you’ll see options like HD, FHD, or WQHD. Pick the highest one available. Your screen might flicker for a second while it applies the change. This tells apps to use your full display capabilities.
Open your problem app again and check. Higher resolution does use more battery, so if you had it set low on purpose, you’ll need to decide what matters more to you. Most modern phones handle maximum resolution just fine without killing your battery too fast.
4. Reset Display Size
Head to Settings and open Display. Scroll until you find Display Size or Screen Zoom. There’s a slider with a preview showing how your screen looks at different sizes.
Move the slider to the middle position marked Default or Standard if it’s anywhere else. Everything on your screen adjusts right away. This resets how apps calculate their display area. Exit settings and test your app.
5. Clear The App’s Cache And Data
Apps sometimes save broken display settings in their cache. Go to Settings and find Apps or Application Manager. Locate your problem app and tap it.
Look for Storage or Storage & Cache and tap that. You’ll see two buttons: Clear Cache and Clear Data. Tap Clear Cache first. This removes temporary files without deleting your login info or settings. Open the app and check if it displays right.
Still not working? Go back and tap Clear Data. This completely resets the app. You’ll have to log in again and set up your preferences from scratch. But it fixes stubborn display issues that nothing else can touch.
6. Check Developer Options
If developer mode is enabled on your phone, go to Settings and scroll down to Developer Options. On some phones, it’s under System or About Phone instead.
Open developer options and scan for anything about screen size or app display. Turn off settings like “Smallest width,” “Force activities to be resizable,” and “Override force-dark.” Every phone has slightly different options here, so read through the list carefully. Look especially for anything mentioning display, size, or screen.
Restart your phone after making changes. Some developer settings only work properly after a reboot.
7. Get Professional Help
Tried everything? Something deeper might be wrong. Hardware problems with your display or corrupted system files can cause issues that regular fixes won’t solve.
A phone technician can run diagnostics you can’t access. They’ll check if your display is damaged or if your Android system needs a complete reinstall. Factory resets sometimes help, but that’s extreme because it erases everything. A technician knows whether it’s actually necessary or if there’s another way.
Wrap-Up
Most full screen problems take just a few minutes to fix once you know where to look. Enable full screen mode in display settings. Update your apps. Check your resolution and display size. Those three fixes solve it most of the time.
Keep your apps updated and check your display settings after any system update. That prevents the problem from coming back. Your entire screen is there to use, so make sure your apps are actually using it.