© 2019 IEEE. User eXperience (UX) evaluation in the field of Mobile Augmented Reality (MAR) is a challenging task, which requires the application of many heterogeneous methods, producing a variety of raw signals and subjective data. This multi-method approach is essential for capturing the holistic UX of any product, service or system. In order to convert this data into information and subsequently knowledge, a comprehensive and scalable system is required which can not only quantify the individual UX metrics but also produce a concise result, which is interpretable by anyone. We call this result, the User Experience Measurement Index, and in this paper we present the results of adopting the mixed method UX evaluation approach for evaluating a prototype MAR application using various methods and sensors, applied before, during, and after its usage. Additionally, we present the methodology and results for calculating the UXMI.