Introduction: Net ultrafiltration rate (NUFR) and net fluid balance (NFB) during pediatric continuous renal replacement therapy (CRRT) are influenced by patient weight and disease state. We investigated how body weight (BW), baseline fluid overload (FO), and capillary leak index (CLI) determine NUFR, NFB, and the FO clearance percentage (FOCP), and related these to hemodynamic changes. Objective: To explore the dynamic relationships among NUFR, NFB, FOCP, FO severity , CLI, and BW during the first 24 hours of pediatric CRRT, and assesses FOCP as a potential simplified prescription target. Methods: This retrospective single-center cohort study (2012–2023) included children receiving≥24 hours of CRRT with complete data. Primary objectives were to quantify how BW , FO, and CLI determine NUFR, NFB, and FOCP. Secondary objectives were to correlate these parameters with hemodynamic changes (? MAPand ? VIS). Results: NUFR was highest in the lowest BW group (5.3 mL kg? ¹h? ¹),declining stepwise to 1.5 mL kg? ¹h? ¹in the heaviest group (p