Measuring user experience in a quantitative way has been on the rise in the user experience community in recent years. Quantifying user experience using KPIs has turned out to be a good way to communicate and negotiate usability problems with product development team, product management team and especially business stakeholders to elevate the importance of usability. In this talk, we will discuss the following best-practices in the IBM Lotus user experience team, and would also like to have interactive discussions with other fellow user experience professionals: - List of most useful user experience KPIs at both task-level and system-level - Gathering KPIs through various user research methods, including not only large-scale unmoderated usability testing or surveys, but also small-scale usability testing, predictive human performance modeling (CogTool), and complexity analysis - Applying standard questionnaires such as SEQ(Single Ease Question), SUS (System Usability Scale) and NPS (Net Promoter Score) for benchmark comparison - Focusing on core tasks and top usability issues