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Background The conventional Lemann Index (LI) assesses cumulative bowel damage in Crohn’s Disease (CD) but may ‘dilute’ the predictive significance of severe localized lesions. This study introduced the Lemann Density Index (LDI)—calculated as the small-bowel LI divided by the number of affected segments—and evaluated its performance in predicting the risk of surgical resection within one year.Methods In this retrospective study of 110 CD patients who underwent computed tomography enterography (CTE), we compared the predictive value of LDI versus the standard LI. Reliability was assessed through a multidisciplinary consensus re-evaluation (radiologist and gastroenterologist) of 25 cases after a 2-month interval. To account for the low event rate (9.1% resection rate), Firth’s penalized logistic regression was employed to identify independent predictors of surgery.Results Ten patients (9.1%) required surgical resection within one year. ROC analysis demonstrated that LDI significantly outperformed the conventional LI (AUC: 0.902 vs. 0.740). An optimal LDI cutoff of ≥ 0.200 yielded 90% sensitivity and 82% specificity. The LDI showed excellent reproducibility (ICC = 0.864; Mean Bias = 0.001). In multivariable Firth’s regression, LDI remained a robust independent predictor (aOR = 11.27 per 0.1-unit increase, p < 0.001), while penetrating behavior (B3) lost statistical significance (p = 0.084). Furthermore, decision curve analysis (DCA) indicated a higher net clinical benefit for LDI over the standard LI.Conclusions The LDI is a reliable and superior predictor of short-term surgical risk compared to the conventional LI. By effectively quantifying lesion intensity and mitigating the ‘dilution effect’ of cumulative scoring, LDI provides a more precise tool for clinical risk stratification and surgical decision-making in CD.