BACKGROUND: BREAST-Q, a patient-reported outcome measure for cosmetic and reconstructive breast surgery, is widely used in both clinical research and practice. The aim of this study was to acquire normative data of BREAST-Q's Breast-Conserving Therapy Module from a Dutch population sample and to compare it with existing normative BREAST-Q values. METHODS: Flyers with QR codes, WhatsApp, and one academic center's Facebook and LinkedIn platforms were used to direct participants to self-complete an online version of four domains of the preoperative BREAST-Q Breast-Conserving Therapy Module. BREAST-Q domain scores were log transformed to normalize the distribution. Univariable regression analyses were used to assess (nonlinear) associations between age and BREAST-Q domain scores. RESULTS: Overall, 9059 questionnaire responses were analyzed. Median (±SD) BREAST-Q domain scores were 64.0 ± 18.0 (satisfaction with breasts), 69.0 ± 21.0 (psychosocial well-being), 92.0 ± 20 (physical well-being), and 59.0 ± 15.0 (sexual well-being). Age as a linear term was associated with log-transformed satisfaction with breasts, psychosocial well-being, and physical well-being; sexual well-being was a quadratic function of age. Previous breast surgery unrelated to breast cancer was a significant predictor for higher log-transformed satisfaction with breasts (β = 0.04, p < 0.001) and higher sexual well-being score (β = -0.05, p < 0.001). Compared with previously published normative data, small differences were found in mean BREAST-Q domain scores (mean differences ranging between 2.45 and 6.24). CONCLUSIONS: Normative Dutch BREAST-Q scores follow similar patterns across domains in comparison with previously published normative data. Normative Dutch BREAST-Q data enable future comparisons in breast-related satisfaction and quality of life issues of Dutch patients with breast cancer compared with their age-matched peers.