We present a generalised phase field formulation for predicting high-cycle fatigue in metals. Different fatigue degradation functions are presented, together with new damage accumulation strategies, to account for (i) a typical S-N curve slope, (ii) the fatigue endurance limit, and (iii) the mean stress effect. The numerical implementation exploits an efficient quasi-Newton monolithic solution strategy and Virtual S-N curves are computed for both smooth and notched samples. The comparison with experiments reveals that the model can accurately predict fatigue lives and endurance limits, as well as naturally capture the influence of the stress concentration factor and the load ratio.