Estimates of stool output in diapers is not an appropriate guideline to use in determining fluid loss through stool. This study was conducted to determine the accuracy of the ability of the nurses (RNs) and patient care technicians (PCTs) to quantify stool volume in diapers. Size 3 diapers, baby food (green peas), and water were used to simulate combinations of stool and urine and differing degrees of water loss in stool. The results indicated that RNs' and PCTs' assessments of stool volume became less accurate as water loss increased. There were no differences in estimation accuracy between RN and PCTs, and years of experience for RNs or PCTs did not influence accuracy of estimation. It is important to use a holistic approach for determining hydration status in patients, particularly knowledge of signs and symptoms of dehydration.