Measuring the impact of technical variables, such as latency, bandwidth, or resources priority-access, on Quality-of-Experience (QoE) of various services demands an extensive feedback from end-users, when those variables change. Estimating QoE in a given scenario becomes harder, when non-technical variables, such as price, need to be considered in addition to technical ones. In any case, detailed feedback that correlates all variables affecting QoE is needed by end-users for each service separately. In this work a deterministic mathematical model (DQX) encapsulating user demands, service characteristics, and variable speciﬁcations is proposed to formalize the QoE calculation, considering one or multiple and diverse variables. The output of QoE functions presented here can be normalized such that results will be compatible with the ﬁve-point scale Mean Opinion Score (MOS), proposed by the ITU-T.