Android has run live wallpapers since 2010, and it shows
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LIVE WALLPAPERANSWERS
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diagramA live wallpaper on Android is a system service rather than an add on, which is why it can respond to a tap, sits behind the home screen properly instead of drawing over it, and stops on its own the moment an app comes to the front.
Android has run live wallpapers since 2010, and that head start shows in how ordinary they are on the platform. Where Windows has nothing built in and iOS accepts only a narrow slice of what a user can supply, Android treats a moving background as a normal kind of thing an app can be. The consequences cut both ways: there are more of them than on any other platform, and their quality and their honesty about permissions vary enormously.
What Android does with a live wallpaper that other platforms do not
Android hosts a live wallpaper as a service the launcher talks to, and that architecture gives it three properties nothing else has. The wallpaper can react, so a tap on the home screen can change what is drawn. The wallpaper is properly behind the icon layer, so notifications, widgets and the app drawer all composite over it correctly. And the system controls its lifecycle, so it is told to stop when the screen turns off or an app covers it rather than having to notice for itself.
That last property is the one that matters for your battery. A moving wallpaper draws power whenever the home screen is visible and nothing when the screen is off or an app is in front of it, and on Android that pause is enforced by the platform rather than left to the developer. A live wallpaper is a video your device never stops playing, but on Android it never plays while you cannot see it.
Where an Android live wallpaper comes from
An Android live wallpaper arrives as an app, which is the first thing to understand about downloading one. There is no loose file format you install into the system: the wallpaper and the code that draws it ship together, and setting it means picking it from the wallpaper chooser after the app is installed. Three kinds are common:
- Dedicated wallpaper apps that ship one scene or a themed set of them.
- Video importers that take an MP4 you already have and register it as a live wallpaper.
- Wallpaper Engine for Android, sold separately from the Steam desktop program, which imports wallpapers made for the desktop version.
Wallpaper Engine is a Steam program that plays video and scene wallpapers on Windows, and its Android companion is the bridge between the two. Its content comes from the Steam Workshop, which is user uploads, so the rights on any given item are whatever the uploader claims. That is worth saying plainly, because an animation loop taken from a series is a copy of that series whichever device it ends up on, and free to download is a statement about a server rather than a license.
The file an Android live wallpaper wants
The file wants to be at least the native pixel count of the panel, and on Android that is a taller frame than artwork is ever composed in.
| Case | Panel | Aspect | What the source has to cover |
|---|---|---|---|
| Mainstream phone | 1080 x 2400 | 20:9 | At least 1080 x 2400 |
| Flagship phone | 1440 x 3120 | 19.5:9 | At least 1440 x 3120 |
| Mainstream phone, parallax launcher | 1080 x 2400 | 20:9 | Roughly 2160 x 2400, about twice the width |
| Flagship phone, parallax launcher | 1440 x 3120 | 19.5:9 | Roughly 2880 x 3120, about twice the width |
The extra width in the bottom two rows is the parallax convention. Android asks for a wallpaper wider than the screen so the launcher can scroll it between home screens, and the conventional guidance is a file roughly twice the screen width where the launcher supports that. Many current launchers no longer scroll, in which case the extra width is simply cropped away. Behavior is launcher specific, and that is the honest answer. A wallpaper is high resolution when it has more pixels than the screen asks for, and a parallax launcher asks for considerably more than it shows.
The aspect ratio is the harder problem. A 16:9 source scaled to fill a 9:19.5 phone has to be about 3.85 times as wide as the screen, so the vast majority of the picture ends up off frame. The same picture is a different file on every device, and a phone is the device that discards the most of it.
Changers, slideshows and themes, which are not live wallpapers
A wallpaper changer swaps one still image for another on a timer, and calling it a live wallpaper confuses two different costs. A changer decodes one image at each swap and does nothing until the next one, so a gallery of stills rotating through the day costs almost nothing, while a live wallpaper renders on every visible frame. If what you want is variety, a changer gives you that at a fraction of the draw, and it lets you keep still images composed with quiet areas behind your icons.
Seasonal sets, such as the Christmas scenes that reappear every December, are usually changers dressed as live wallpapers, and theme packs bundle a wallpaper with icon and color changes that have nothing to do with motion. It is worth reading which of the three you are installing.
What a black wallpaper actually saves on an AMOLED phone
A black wallpaper saves real power on an AMOLED phone and nothing at all on an LCD one. An OLED subpixel showing pure black is switched off, so a genuinely black area costs close to nothing to display, while an LCD keeps its backlight on regardless. That is the mechanism behind every recommendation of black and near black wallpapers you see discussed on Reddit, and why a dark live wallpaper is a smaller ask than a bright one on the same phone.
Choosing a wallpaper app without handing over the phone
Choose an Android wallpaper app the way you would choose anything that runs at boot, because a live wallpaper service does exactly that. Check what permissions it asks for, and be suspicious of anything wanting contacts, location or accounts to draw a picture. Check whether it needs the network once the wallpaper is downloaded. Check whether the wallpapers inside it are credited, because an app full of uncredited artwork is an app selling somebody else's work. And check its frame rate or quality setting, because the difference between the default and a sensible value is the difference between noticing the battery and not.