The present paper proposes a method for the geometric calibration of a new endoscopic ultrasound (US) probe designed for the imaging of the inner ear. Such US probe has 24 elements and a distal diameter equal to 4 mm. The atypical probe miniaturized geometry may raise doubts about the applicability of existing state-of-the-art calibration methods. This work answers such question. The results presented in this paper indicate that the proposed straightforward calibration procedure leads to satisfying accuracy. The phantom used for the geometric calibration have wires as reference geometry and its dimensions are taken based on a microtomography acquisition. The obtained results may enable the US imageguided navigation of the human inner ear.