What is a good blood preasure for 12 year old?

For children and adolescents between the ages of 1 and 18 years: Blood pressure categories can differ depending on age, sex, and height so consult with a pediatrician

Systolic (upper value) and diastolic (lower value)

Normal: Lower than 120 over 80 mm Hg

Prehypertension:

<130 mmHg

<80mmHg.

High blood pressure (stage 1 hypertension):

Systolic =130 to 139 or Diastolic 80 to 89 mm Hg

*High blood pressure (stage 2 hypertension): Systolic 140 or higher/Diastolic 90 or higher mm Hg