Calculadora IG e percentil is a free Android application developed by Ricardo Sousa-Santos for health professionals, including specialists in obstetrics, family medicine, neonatology, and pediatrics. This app allows the calculation of the percentile of fetal estimated weight/RN weight adjusted for fetal sex, based on a wide sample of pregnancies dated by CRL of the Portuguese population. Additionally, it enables the calculation of gestational age based on the date of the last menstrual period, date of conception, probable date of delivery, or from an ultrasound with dating long caudal skull. You can calculate a date from a gestational age or vice versa. The app also allows you to calculate the estimated weight by ultrasound from the biometric parameters according to the Hadlock formulas 2 and 4 parameters. The study data that the app is based on can be found in the European Journal of Obstetrics and Gynecology and Reproductive Biology, Volume 206, .