Windows has no live wallpaper of its own

That one architectural fact decides everything else on this page. There is no setting to enable, no supported file format to look for, and no Microsoft feature to compare products against. What exists instead is a small set of programs that draw their own window behind your icons and keep redrawing it, and choosing between them is mostly a question of what you are willing to install.

Why the Windows desktop cannot do this by itself

The Windows desktop cannot animate a background because it was built to hold one picture, composited once and then left alone. It goes further than that: Windows re-encodes the desktop wallpaper as JPEG by default, which is why a clean PNG can look blocky the moment it is set. That behavior is controlled by a JPEGImportQuality value under HKEY_CURRENT_USER\Control Panel\Desktop, set as a DWORD from 60 to 100, and raising it to the maximum is the single most useful thing most people can do to a still Windows wallpaper.

A live wallpaper program works around all of this rather than through it. It creates a window, parents it behind the desktop icon layer, and renders into it continuously. The operating system is not involved beyond hosting the window, which is why these programs have to run at login, why they each have their own file format, and why nothing you set up in one of them transfers to another.

The programs that do it on a PC

Wallpaper Engine is a Steam program that plays video, scene and web page wallpapers, and it is the one most people mean when they talk about live wallpaper on a computer. It has no macOS build and none has been announced, it runs on Linux and the Steam Deck through Proton unofficially rather than with support, and there is a separate Wallpaper Engine for Android that imports wallpapers from the desktop version. There is no iOS version. Its content comes from the Steam Workshop, which is user uploads, so the rights on any given item are whatever the uploader claims and frequently the uploader did not make the art.

What to check before installing a wallpaper program

Check five things before you install any wallpaper program, because a program of this shape starts at login and draws on your desktop, which is more access than a decoration normally earns.

1. Verify the publisher and get the installer from the store or repository that publisher actually uses.
2. Check whether it pauses when another application is fullscreen or maximized, since that single behavior decides its cost in games and on battery.
3. Check what it wants from the network, and whether it needs anything beyond fetching the wallpapers you ask for.
4. Check its quality and frame rate settings, and set them down to what your screen actually needs rather than leaving the default.
5. Check the license on every wallpaper you load into it, because the program's rights and the artwork's rights are two different questions.

The size a computer wallpaper has to be

The size a computer wallpaper has to be is the native pixel count of the panel, and for a live wallpaper that is a demand on every frame rather than on one image.

Two points about that table are worth stating plainly. A monitor advertised as 4K is almost always 3840 x 2160 and not DCI 4K at 4096 x 2160, which is a cinema standard. And 3840 x 2160 is four times the pixels of 1920 x 1080, not twice, so a 1080p loop stretched across a 4K panel is being invented three quarters out of nothing. Windows can span a single picture across two displays with the Span option, so two 2560 x 1440 monitors want one file at 5120 x 1440. The same picture is a different file on every screen, and an ultrawide is the least forgiving of them, because cropping a 16:9 source to 21:9 keeps only about 74% of the original height and cuts roughly 13% off the top and the same off the bottom.

A live wallpaper against a still design

A live wallpaper and a still design differ in one measurable way and several matters of preference. The measurable one is that a still image is composited once and then costs nothing, while a live wallpaper costs work on every frame it is visible for. Everything else follows from what you do with the machine: someone who works in fullscreen applications will barely see a live wallpaper, and someone who keeps a clear desktop between tasks will see it constantly and pay for it constantly. A still design also lets you place quiet areas where your icons sit, which a moving scene cannot promise from one second to the next.

Making your own instead

Making your own wallpaper for free removes the rights question entirely, which is the one problem no program on this page can solve for you. A design tool such as Canva, or any editor that lets you set an exact canvas size, will do it: start the canvas at the native resolution of your screen, work at that size rather than scaling up at the end, and export to PNG for flat color and line art. Free to download and free to use are not the same thing, and the file you made yourself is the only one where the distinction never comes up.

Where to go next

DEVICESYour desktop, your phone and your tablet each want a different wallpaper fileWallpaper sizes by deviceWALLPAPER ENGINEWallpaper Engine is a Steam program that plays things on your desktopWallpaper Engine, explainedLIVE WALLPAPERA live wallpaper is a video your device never stops playingWhat it is and what it costsFREE TO USEFree to download and free to use are not the same thingWhere a free anime background actually comes from