The volume of a toddler's mouthful needs to be defined to estimate poisoning risk. We calculated a toddler's mouthful in 66 healthy children (1.5-4.5 years old) by measuring apple juice remaining in a cup after sipping. Mean volume was 9.3 mL (range, 3.5-29; 95% confidence interval, 8-11), twofold larger than commonly quoted values.