BACKGROUND: Although the beauty of the breast depends on aesthetic proportions, the position of the nipple-areola complex (NAC) on the breast mound and in relation to the implant during breast augmentation or mastopexy augmentation is critical. In fact, lack of nipple position determination in relation to the breast footprint is a deficiency of most currently applied measurements and evaluation tools. The authors hereby present a simple formula that allows accurate and proper prediction of the ideal NAC positioning for every patient depending on the chosen implant in case of mastopexy augmentation, or revision mastopexy with exchange of implants. METHODS: A prospective level IV analysis of all consecutive patients undergoing primary mastopexy augmentation or revision mastopexy with exchange of implants was performed between January of 2021 and January of 2022. Forty-eight consecutive patients were included in the study. The nipple-inframammary fold-upper breast border (NIU) principle was applied to all patients to determine the ideal position of the NAC. Patients were photographed preoperatively and postoperatively in a standardized manner. The main endpoint was to determine whether the NAC is located at the most projected point of the breast on follow-up. RESULTS: The NIU principle was applied to 48 patients between January of 2021 and January of 2022. Of those patients, 27 underwent primary augmentation mastopexy, and 21 underwent revision augmentation mastopexy with exchange of implants. The mean follow-up duration was 9.2 months (range, 6 to 18 months). All patients demonstrated proper NAC positioning on follow-up. CONCLUSION: The NIU principle is a simple and reliable method to determine the ideal NAC position during mastopexy augmentation or mastopexy with implant exchange. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.