Screen Size / File Type for Wallpaper

[Satori]

If I want to save a picture to use as a wallpaper, what size and file type should I save it as?

Thanks!

 

[GalaxyS609]

I just made one today, it was 1280 x 800, but it was a little wider than needed. I just saved it as a 60 Quality JPG since there wouldnt have been any noticeable different going higher or saving as a PNG.