Flexible phased arrays can address new applications and provide new capabilities in communications, radar, sensing, and wireless power transfer due to their novel form factor, which enables rapid deployment, conformity, and mass and size advantages. However, the variable position of their elements makes them vulnerable to the deleterious effects of incoherence. This problem can be addressed by reconstructing the shape of the array and compensating for the change in the position of the radiator at the system level. This article presents a method for reconstructing the shape of a 2-D flexible phased array using only measurements of mutual coupling between the array elements. The method consists of an optimization loop: predicting the coupling for a given shape, comparing the prediction to measurement, and iterating through shape perturbations using the Levenberg–Marquardt algorithm. Shape reconstruction is demonstrated with a ≈ 0.08 λ mean position error across a wide variety of shape configurations on a passive 8 × 8 flexible patch antenna array operating at ≈ 5 GHz.