What is the normal blood pressure for a teenager?

According to TeensHealth, normal blood pressure for a teenager under 18 varies, with the normal range falling below the 90th percentile for that teenager's age, gender and height. Eighteen and 19-year-olds should have no higher than a 120 systolic over 80 diastolic reading, which is also normal for an adult.

The National Heart, Lung and Blood Institute has a table that lists normal ranges for teenagers. For example, at age 13, the highest normal blood pressure for boys in the 95th percentile for height is less than 126 systolic over 79 diastolic. Girls the same age in the 95th percentile for height should have blood pressure no higher than 124 systolic over 79 diastolic.