Abstract Background/aim: Symptomatic breast hypertrophy has a significant impact on the quality of life of women. The amount of tissue to be excised may be preoperatively estimated by an experienced surgeon. However, this remains a subjective assessment. Accurate quantification of the amount of breast tissue to be resected in the preoperative period will be a guide for both patient information and the surgeon during the operation. The aim of this study is to develop a new method based on simple measurements that can accurately estimate the resection weight in the preoperative period in a wide range of patients undergoing reduction mammoplasty. Materials and methods: The study was carried out between December 2016 and September 2018. With the determined drawing and measurement methods, a triangle was obtained by measuring the distances among the sternal notch (A) - right nipple areola midpoint (B), sternal notch (A) - left nipple areola midpoint (C) and both internipple areola (B-C). The height of this triangle (h) was found by measuring the distance between the sternal notch and the midpoint of both nipple areola levels. The amount of breast tissue to be resected for each breast was calculated by multiplying the distance between the sternal notch–nipple areola and the height of the large triangle. The formula may be expressed as AB × h for the right breast and AC × h for left breast. Results: When the t values and significance levels of the beta coefficients of the independent variables were examined, the preoperative values were determined to be in accordance with the actual values after surgery (P < 0.05). The values calculated before were calculated as the percentage of the actual values (91%). In other words, the R2 value showed that the calculated values were compatible with the actual values (R2 = 0.910). Conclusions: With the formula described herein, one may accurately estimate the amount of tissue to be resected in a wide range of patients undergoing reduction mammoplasty whose sternal notch–nipple distances are between 28–42 cm. Additionally, because measurements for each breast are performed separately, breast asymmetry does not affect the results. In conclusion, the formula we devised is simple, applicable, and has a high accuracy rate.