The most used size for desktop wallpapers is 1920×1080 pixels.
If you have a 4K screen, then you need a 3840×2160 pixels wallpaper
picture size.
If you need a custom wallpaper image for your smartphone, we suggest setting
the dimensions to 1080×1920 pixels.
Using PixTeller's wallpaper maker editor you can manually insert custom width and height values,
so you can make your own background pictures in any size.