What Is The Screen Resolution For The iMac 27? The iMac 27-inch boosts a resolution of 2560 by 1440 pixels. The iMac 21.5-inch has a resolution of 1920 x 1080 pixels. So while the iMac 27-inch is... Read answer Asked by Lisa M. on November 30th, 2010 Filed Under: iMac, iMac 27, iMac 27-inch, Screen Resolution, iMac 21.5, iMac 21.5-inch