*1GB = 1 billion bybtes: actual formatted capacity less
** Testing conducted by Apple in February 2015 using pre-production 1.2GHz Intel Core M-based 12-inch MacBook systems with 512GB of flash storage and 8GB of RAM. The wireless web test measures battery life wirelessly browsing 25 popular websitres with display brightness set to 12 clicks from bottom or 75%. The HD film playback test measures battery life by playing back HD 1080p content with display brightness set to 12 clicks from bottom or 75%. Battery life varies by use and configuration. See www.apple.com/uk/batteries for more information.