Pediatric Blood Pressure Calculator — BP Percentile by Age

Formula

How this is calculated

Pediatric blood pressure norms differ markedly from adult values and vary by age, sex, and height. The reference standard is the NHLBI "Fourth Report on the Diagnosis, Evaluation, and Treatment of High Blood Pressure in Children and Adolescents" (2004), which provides normative tables from 73,000 measurements. The 2017 AAP Clinical Practice Guideline (Flynn et al., Pediatrics 140:e20171904) adopted the same normative data but updated classification terminology: "normal" (<90th percentile), "elevated" (90th to <95th, or ≥120/<80 mmHg if that is lower), "Stage 1 hypertension" (95th to <95th+12 mmHg), and "Stage 2 hypertension" (≥95th+12 mmHg or ≥140/90 mmHg).

This calculator uses approximate 90th-percentile values at the 50th height percentile — the midpoint of a child's expected height for their age and sex. Height shifts the thresholds by a few mmHg in either direction: a tall child has slightly higher normal limits than a short child. For precise clinical classification, practitioners use the full normative tables provided in the NHLBI report or the AAP guideline supplement, entering the child's actual height percentile.

Because blood pressure in children can be white-coat-elevated or transiently high from crying or activity, the AAP guideline recommends confirming hypertension with repeat measurements on two or more separate occasions, using the appropriate cuff size, and measuring from the right arm with the child seated and at rest for five minutes.