🧮 Pediatric BP Percentile Calculator

AAP 2017 Clinical Practice Guideline — Children and Adolescents Ages 1–17

Why height and not age? Blood pressure has to push blood up to the brain, so the pressure a child needs scales with the length of that column — not with birthdays. A tall 7-year-old legitimately needs a higher pressure than a short one. That is why every threshold below is indexed to sex, age and height percentile. The reasoning is worked through in the pediatric hypertension lecture.

Patient data

Enter sex, age, height, and blood pressure.

Result

Results will appear here.

How this calculator works

📏 Height percentile

Computed from the CDC 2000 growth reference using the published L, M and S parameters at the child's exact age in months — recumbent length below 36 months, standing stature above it, which is the same convention the AAP tables use.

📈 BP percentile

Anchored exactly on the guideline's published 50th, 90th and 95th percentile values, with monotone interpolation between them. At a published threshold the calculator returns that percentile exactly — it can never disagree with the table at a decision point.

🎯 Staging

Ages 1–12 are staged on percentiles, taking the lower of the percentile and the static adult cut-point. Ages 13–17 are staged on the static thresholds alone, matching the guideline's alignment with adult AHA/ACC criteria.

Cuff size first, arithmetic second. The commonest cause of a falsely hypertensive child is a cuff that is too small. The bladder should be at least 40% of mid-arm circumference and should encircle 80–100% of the arm. Measure in the right arm, seated, feet on the floor, after 3–5 minutes of rest, and confirm any elevated automated reading by auscultation — the percentile tables were built from auscultatory data.
This is an educational tool, not a diagnosis. A diagnosis of hypertension requires elevated readings on three separate occasions. Results should be interpreted by a clinician alongside the growth chart, the history and the physical examination. Ages under 1 year are not covered — neonatal blood pressure uses a different reference entirely.

Source and verification

Threshold values are taken from Flynn JT, Kaelber DC, Baker-Smith CM, et al. Clinical Practice Guideline for Screening and Management of High Blood Pressure in Children and Adolescents. Pediatrics. 2017;140(3):e20171904 (PMID 28827377), Tables 4 and 5, extracted programmatically rather than transcribed by hand.

Every cell was checked for internal arithmetic consistency, percentile ordering and monotonicity across height. The boys' table was compared cell by cell against an independently sourced copy of the same table — 1,190 of 1,190 cells identical. Height columns were validated against the CDC 2000 growth reference and agree to within 0.06 cm across ages 3–17.

Andrew Bland, MD, FACP, FAAP · Nephrology Education