The suprameatal triangle is used for approaching the tympanic cavity and also it is an important landmark for otologic surgeons during mastoidectomy. Aim: To determine the depth of sigmoid sinus plate over the Macewan’s triangle by morphometry of various anatomical landmarks. Materials & Methods: The study was carried out in the Department of Anatomy, Penang International Dental College & VMKV Medical College, Salem on 30 dry human adult skulls. Five landmarks (D1, D2, D3, D4, D5 and D6) were taken on the left and right sides of the skulls and the imaginary lines were constructed and measured by Vernier caliper between the landmarks. Results: The measurement of D2 showed statistically significant differences. The correlations of D1, D3, D4, D5 and D6 on both sides do not show any significant differences. The linear correlation equations were derived using the measurements for predicting D6. Conclusion: The depth of sigmoid sinus plate (D6) can be assessed using D1, D2, D3, D4, D5 on lateral view of head & neck X-rays which can be used by Otologist during mastoidectomy to avoid severe bleeding complications from sigmois sinus. © 2021 Elsevier B.V., All rights reserved.