Background There have been conflicting reports on how sagittal synostosis affects cranial vault volume (CVV) and which surgical approach best normalizes skull volume. In this study, we compare CVV and cranial index (CI) of children with sagittal synostosis (before and after surgery) to those of controls. We also compare the effect of repair type on surgical outcome. Methods CT scans of 32 children with sagittal synostosis and 61 age- and gender-matched controls were evaluated using previously validated segmentation software for CVV and CI. 16 cases underwent open surgery and 16 underwent endoscopic surgery. 27 cases had both preoperative and postoperative scans. Results Age of subjects at CT scan ranged from 1-9 months preoperatively and 15-25 months postoperatively. Mean age difference between cases and matched controls was 5 days. The mean CVV of cases preoperatively was non-significantly (17cc) smaller than controls (p = 0.51). The mean CVV of postoperative children was non-significantly (24cc) larger than controls (p = 0.51). Adjusting for age and gender, there was no significant difference in CVV between open and endoscopic cases postoperatively (β = 48cc, p = 0.31). The mean CI increased 12% in both groups. There was no significant difference in mean postoperative CI (p = 0.18) between the two groups. Conclusions Preoperatively, children with sagittal synostosis have no significant difference in CVV compared to controls. Type of surgery does not seem to affect CI and CVV one year postoperatively. Both open and endoscopic procedures result in CVVs similar to controls.