Sulcal emergence is important to assess normality of early fetal brain development. Thus, we proposed a quantitative approach to build an accurate timetable of sulcal emergence. Using a large sample of fetuses, we automatically extracted cortical surfaces and detected presence and absences of each sulcus. By fitting a logistic curve to sulcal presence/absence, the timing and inter-subject variability of sulcal emergence were estimated. We also found hemispheric asymmetry and sex difference in the timing and variability of sulcal emergence. Our quantitative timetable concurs with previous reports but provides more precise information and allow statistical comparison.