In the evolving landscape of web and mobile applications, traditional metrics like APDEX and W3C navigation timings have become inadequate for assessing user experience due to changes in technology such as AngularJS and the shift to single-page applications. The proposed User/Customer Experience Index provides a modern framework that evaluates user experience through five key components: User Journey, User Action Performance, Errors, User Behavior, and User Environment. By focusing on these ingredients, the User Experience Index measures satisfaction levels by analyzing user actions, performance, and errors, as well as behavioral patterns and environmental factors like network conditions. This approach allows for a nuanced understanding of user satisfaction, categorizing experiences as satisfied, tolerating, or frustrated, which helps improve user experience by addressing technical issues rather than superficial changes.