Objective: This study aimed to assess whether estimations made by groups of two or three healthcare professionals were more accurate than those made by a single observer when estimating the weight of supine adult patients in the emergency department (ED). Methods: This prospective observational study was conducted in a tertiary hospital’s ED in Jeddah, Saudi Arabia. Adult ambulatory patients (aged 18 years or older) were enrolled using systematic random sampling. Each patient underwent three sequential weight estimations: (1) single emergency physician, (2) physician–nurse pair, and (3) triad of physician, nurse, and another emergency provider. Observers were blinded to prior estimates and actual weight, which was measured using a calibrated hospital scale. Accuracy was defined as ±5 kg of the actual weight. Data were analyzed using repeated measures analysis of variance and Bland–Altman plots. Results: A total of 369 patients were included (52.3% female; mean age, 50.38 years). Accuracy rates were 67.5%, 74.0%, and 76.4% for single observers, pairs, and triads, respectively (p < 0.05). Board-certified emergency physicians had the highest accuracy across all configurations (up to 88.8%), followed by residents and non-board-certified emergency physicians. Collaborative estimation improved accuracy, with the largest relative gain among general practitioners (38.0%–63.0%). The triads demonstrated the smallest variance in error. Conclusion: Compared with individual assessments, collaborative weight estimation improves accuracy and might enhance patient safety when direct measurement is not feasible. In high-volume, resource-limited EDs, structured, interprofessional protocols should be considered.

Keywords: Emergency service, body weight/methods, observer variation, interprofessional relations, Saudi Arabia.