Background: The waste products of metabolism and extra water are eliminated by the kidneys. The kidneys are reddish-brown when they are fresh. The average dimensions of a kidney are 3 cm in the anteroposterior direction, 6 cm in width, and 11 cm in length. The left kidney may be 1.5 cm longer than the right. Objective: The objective of the study is to determine the gestational age of fetuses based on fetal kidney length. Material and Methods: This study was conducted on 96 normal sonographs of pregnant women in 2nd trimesters in the Department of Anatomy, in collaboration with Obstetrics & Gynecology and Radiology of Index Medical College Hospital & Research Centre, Malwanchal University, Indore. This study was carried out for a period of 2 and a half years (from July 2021 to December 2023). Observation & Result: From this study, we calculated the mean value and standard deviation of fetal kidney length in group A (18-21) is 18.54±2.55, and group B (22- 25) is 19.71±2.22 weeks. The mean and standard deviation of fetal kidney Width in group A (18-21) is 11.81±2.16, and in group B is 14.18±2.89 weeks. The mean and standard deviation of fetal kidney Thickness in group A (18-21) is 9.81±2.37, and in group B is 11.37±1.66 weeks. Conclusion: From this study, we conclude that FKL is a good and accurate indicator for the measurement of GA, especially in the second trimester. FKL correlated very strongly with GA compared to other parameters. Hence in the second trimester, FKL can be used for better prediction of GA.