How long is the average person's mouth?

The average adult human mouth is approximately 2.5 to 3 inches (6 to 7.5 centimeters) wide when fully open. However, this measurement can vary based on individual anatomy. The length from the front of the lips to the back of the throat is generally around 4 to 5 inches (10 to 13 centimeters). Keep in mind that these values can differ among individuals.