WallpapersWide.com - Free High Quality Desktop Backgound Wallpapers in 4K & 8K UHD for Ultra HD TV, Ultra Widescreen Desktop, Tablet, Smartphone & Multi Display gaming setups for nView & Eyefinity (Dual & Triple monitor configuration)

Screensiz.es is a handy database of screen sizes, viewport sizes, and pixel densities for popular smart phones, tablets, and monitors.