Formulae are derived for the resolution of the geoid undulations by degree implied by mean gravity anomalies. The two error sources considered are the propagation of the mean anomaly errors and the error due to lack of more detailed data than the mean anomalies. The errors are computed for the degree variances of Tscherning and Rapp and the β function of Meissl. Finally, the corresponding errors of point gravity anomalies are derived.