The average resting heart rate for a 12-year-old is anywhere between 60 and 100 beats per minute. Any child over the age of 10 has the same average heartbeat as an adult.
As a child grows older, their resting heart rate slows down. Furthermore, if the 12-year-old is engaged in regular physical activity, the resting heart rate is typically lower. A well-trained athlete, for example, has a resting heart rate between 40 and 60 beats per minute. A child should seek medical attention if their resting heart rate is significantly faster or slower than the average of 60 to 100 beats per minute.