Surface Book 3 13.5” on base: Up to 15.5 hours of battery life based on typical Surface device usage. Testing conducted by Microsoft in April 2020 using preproduction software and preproduction configurations of Surface Book 3 13.5” Intel® Core™ i5, 256GB, 8 GB RAM. Testing consisted of full battery discharge with a mixture of active use and modern standby. The active use portion consists of (1) a web browsing test accessing 8 popular websites over multiple open tabs, (2) a productivity test utilizing Microsoft Word, PowerPoint, Excel and Outlook, and (3) a portion of time with the device in use with idle applications. All settings were default except screen brightness was set to 150nits with Auto-Brightness disabled. Wi-Fi was connected to a network. Battery life varies significantly with settings, usage and other factors.