For many applications in MRI fast and accurate $$$B_1^+$$$ -mapping is an important prerequisite to correct for spatially varying RF-field variations. We recently proposed a reconstruction algorithm to reconstruct highly undersampled Bloch Siegert data, which was applied to 3T data. In this work we investigated the applicability of this algorithm to 7T data in terms of accuracy and possible acquisition time. We could successfully show that the proposed algorithm can be applied to 7T data with only slightly increased error compared to 3T. The minimum scan time at 7T is in the order of 45s-1min for a 3D volume.