Mean Opinion Score Calculator

Mean Opinion Score (MOS) is a qualitative measurement of voice quality on a telephone connection. MOS scores range from 0 (pure noise) to 5 (perfect fidelity). People who build telephone systems generally aim to achieve a MOS score of 4 or better, though special capabilities can offset a decline in quality in some cases (as in mobile phones).

MOS can be measured qualitatively, by a panel of human testers. However, it's often more efficient to used measured values to calculate it. Two useful standards documents -- ITU G.107 and G.113 Appendix I -- define the E-Model, an algorithm for calculating MOS from measured factors.

This calculator takes into account codec choice, packet loss, end-to-end delay, and jitter, and yields a MOS value. It is meant for VoIP applications. Note that this is a modified E-Model implementation, since the standard E-Model does not take jitter into account.