The cranial index (CI) of Ghanaians is currently unknown. The aim of this study was to measure the CI in a population of Ghanaians in order to classify them against pre-determined CI categories. A systematic random sampling method was used to select 300 normal computed tomography (CT) head scans of adult Ghanaians from the largest hospital in Ghana. All patients were deemed to have a normal cranial image configuration based on the radiological report. The biparietal diameter (BPD, width) and the occipitofrontal diameter (OFD, length) were measured on transaxial CT images using a workstation with a calibrated measurement calliper tool. The CI ratio was calculated as the BPD multiplied by 100 and divided by the OFD. Mean, standard deviation (SD) and range were calculated for BPD, OFD and CI. Differences in measurements between demographic groups were compared using an unpaired t-test, with test α set at 0.05. Of the population of Ghanaians included in this study, 165 (55%) were male and 135 (45%) were females. The mean CI was 77.3 ± 3.6 in males and 79.0 ± 3.3 in females, placing both genders in the mesocephalic category. However, the difference between males and females was found to be statistically significant (P = 0.02). The study indicated that most Ghanaian adults belong to the mesocephalic category of CI. Females also had a higher CI, which could be used to differentiate gender groups. This information can be useful for forensic medicine, plastic surgeries for clinical and research purpose. KEY POINTS• This study found the mean CI of adult Ghanaians to be 78.0 ± 13.0.• This indicates that most Ghanaian adults belong to the mesocephalic category of CI.• Females had a higher CI, which could be used to differentiate gender groups.• To the best of our knowledge, this is the first study which assessed CI of Ghanaians using CT scan.