How big is the average 10 year old mouth?

The average size of a 10-year-old's mouth can vary significantly, but generally, the width of the mouth is around 2.5 to 3 inches (6.4 to 7.6 cm) when fully open. The height from the upper lip to the bottom lip is typically about 1 to 1.5 inches (2.5 to 3.8 cm). Individual variations depend on factors like genetics and overall growth, so these measurements can differ among children.