Background: Establishing cutoff values for low birth weight (LBW) and high birth weight (HBW) is crucial for clinical practice. This study aimed to determine these values in Saudi Arabia. Method: A retrospective study in 2022 analyzed the birth weights of 1605 neonates. The 10th and 90th percentiles were calculated to define LBW and HBW. Results: LBW was defined as 3650 g (90th percentile), with a prevalence of 10.3%. Comparing the WHO’s LBW definition (<2500 g) revealed significant differences but high agreement (kappa = 0.962). HBW had a prevalence of 2.4% using a 4000 g cutoff, with low agreement (Kappa = 0.357). Conclusions: This study suggests an LBW cutoff at 2450 g and an HBW cutoff at 3650 g in Saudi Arabia. A birth weight range of 2450–3650 g is considered normal, reducing unnecessary healthcare interventions.
