Objectives: Severity of unilateral coronal synostosis (UCS) can vary. Quantification is important for treatment, expectations of treatment and natural outcome, and education of the patient and parents. Design: Retrospective study. Setting: Primary craniofacial center. Patients, Participants: Twenty-three preoperative patients with unilateral coronal craniosynostosis (age < 2 years). Intervention: Utrecht Cranial Shape Quantifier (UCSQ) was used to quantify severity using the variables: asymmetry ratio of frontal peak and ratio of frontal peak gradient. Main Outcome Measures(s): The UCSQ variables were combined and related to visual score using Pearson correlation coefficient; UCSQ and visual score were additionally compared to Di Rocco classification by one-way analysis of variance or Kruskal-Wallis test. All measurements were made on computed tomography scans. Results: Good correlation between UCSQ and visual score was found (r = 0.67). No statistically significant differences were found between group means of UCSQ in the 3 categories of Di Rocco classification (F2,20 = 0.047; P >.05). Kruskal-Wallis test showed no significant differences between group means of visual score in the 3 categories of Di Rocco classification (Kruskal-Wallis H (2) = 0.871; P >.05). Conclusions: Using UCSQ, we can quantify UCS according to severity using characteristics, it outperforms traditional methods and captures the whole skull shape. In future research, we can apply UCSQ to 3D-photogrammetry due to the utilization of external landmarks.