Introduction <p>This study aimed to investigate which of the STONE, Clinical Research Office of the Endourological Society (CROES), stone‒kidney size (SKS), Seoul National University Renal Stone Complexity (S-ReSC) and Guy’s nephrolithometry scores are more effective in predicting stone-free rates and postoperative outcomes after percutaneous nephrolithotomy (PCNL) in obese patients.</p> Methods <p>The study data were retrospectively obtained from the electronic medical records of obese patients (body mass index (BMI) &gt; 30&#xa0;kg/m²) who underwent PCNL at a single center between February 2022 and July 2025. The data were evaluated in accordance with the Declaration of Helsinki with ethics committee approval. Patients were examined in two groups: a residual fragment group and a stone-free group.</p> Results <p>A total of 295 patients were included; 205 were stone free, whereas 90 had residual stone fragments. The long axis length, surface area, volume, and proportion of staghorn stones were significantly greater in the residual fragment group (<i>P</i> &lt; 0.001). Guy’s and SKS scores were significantly greater in the residual fragment group, whereas the CROES score was significantly greater in the stone-free group. No significant differences were observed for the STONE or S-ReSC scores. In receiver operating characteristic (ROC) analysis, the CROES score demonstrated 80% sensitivity and 67% specificity at a cutoff value of 195. The sensitivities of the Guy’s and SKS scores were 87% and 83%, respectively, with specificities of 47%. In multivariate analysis, the CROES score, stone long axis, and Guy’s score were identified as independent predictors of residual stone fragments. Postoperative complications were also evaluated, although no scoring system demonstrated a significant ability to predict complications.</p> Conclusion <p>Our data reveal that the CROES provides the most accurate estimate of stone-free success in obese individuals.</p>