Background/aim: The aim of this study was to perform morphometric analysis of the foramen magnum (FM) using cone-beam computed tomography (CBCT). Materials and methods: This study included CBCT images of 190 individuals (88 males and 102 females). The sagittal and transverse diameters and circumference of the FM were measured. The shape of FM was classified as round, hexagonal, oval, egg-shaped, tetragonal, pentagonal, irregular A, and irregular B. The data were statistically analyzed with chi-square and t-tests to assess the level of significance for sex and age. Results: The means of its sagittal and transverse diameters and also circumference were higher in males than in females. Statistically significant differences were found between males and females for all variables (P < 0.05). No statistically significant difference (P > 0.05) was found between age groups for all variables. The round type was the most common, in 21.6% of the patients. Conclusion: CBCT images can provide valuable information regarding FM and the measurements of its sagittal and transvers diameters and also its circumference may be reliably used for sexual dimorphism in anthropometric analysis and forensic medicine.