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Child BMI Percentile Calculator

BMI-for-age percentile on the CDC reference, ages 2-20 — the percentile, not the BMI, is what counts for a child.

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Height Percentile CalculatorWhere your height sits against the US adult reference, with the z-score and standard-deviation band.BMI calculatorCompute your Body Mass Index and weight category.Target weight for a BMI calculatorFind the body weight that matches a target BMI for your height.Baby Growth Percentile CalculatorWeight, length and head circumference percentiles from the WHO Child Growth Standards, 0-24 months.Am I Overweight? CalculatorFind out if you're overweight from your BMI, with your healthy weight range and kg to reach it.Am I Underweight? CalculatorFind out if you're underweight from your BMI, with your healthy weight range and kg to reach it.Biological Age CalculatorEstimate your biological age from lifestyle factors — fitness, diet, sleep, stress and more. Educational, not medical.Body Frame Size CalculatorSmall, medium or large frame from your height-to-wrist ratio, with a frame-adjusted weight range.

Child BMI Percentile Calculator is free to use as often as you like, directly from this page. It sits under Weight & body in our catalogue, alongside Height Percentile Calculator and BMI calculator.

How to use it

  1. Open the tool — no signup or install needed.
  2. Enter your input or adjust the available options.
  3. Get your result instantly, then copy or download it.

Frequently asked questions

What is Child BMI Percentile Calculator?

BMI-for-age percentile on the CDC reference, ages 2-20 — the percentile, not the BMI, is what counts for a child.

When would I actually use this?

Getting a reference point before a check-up, setting a realistic target, and understanding why two people of the same weight can be in very different shape — and, the same act from the other side, putting a day's caffeine, salt, sugar or alcohol beside the ceiling a health body publishes for it.

What is the most common mistake?

Reading BMI as a measure of health. It cannot tell muscle from fat, which is why athletes routinely score as overweight and why it says little about an individual.

How is Child BMI Percentile Calculator different from Height Percentile Calculator?

They sit next to each other but answer different questions: Height Percentile Calculator is the one to open when you need it to where your height sits against the US adult reference, with the z-score and standard-deviation band. Pick whichever matches what you're starting from — both are free.

Is there a tool for the next step?

BMI calculator is the closest one after this: Compute your Body Mass Index and weight category.

What else is worth having open alongside it?

Target weight for a BMI calculator and Baby Growth Percentile Calculator — they come up in the same task often enough to be worth a second tab.

Where do the figures come from?

The CDC 2000 BMI-for-age reference for ages 2–20, boys and girls, read from the LMS parameters as CDC publishes them and on CDC's own half-month age grid — not resampled to half-years. A child's BMI percentile is age- and sex-specific by construction, which is why an adult BMI category means nothing here. It describes where one measurement falls in a US reference population from 2000; it does not measure body composition and it is not a diagnosis.

Further reading

All guides →
ExplainerGrowth Percentiles: What a Child's Centile Really MeansA centile ranks a child against a reference population — it is not a grade, and one reading says almost nothing. Here is the LMS arithmetic behind the number, and why the same boy is on the 90th centile on one chart and the 85th on another.ExplainerHow Tall Will a Child Be? The Arithmetic Is Easy; the Error Bar Is the StoryAverage the parents' heights, shift by a sex constant, and you have a target height. The honest part is what comes next: the published prediction interval is about ±4 inches, wide enough to cover most of the adult population. Here is the formula, the interval, why bone age does better, and why children keep out-growing the target.ExplainerBaby Growth, and What Crossing Centiles Actually MeansThe WHO infant standard is prescriptive: it was built from healthy breastfed babies and describes how infants should grow. National references describe how they did grow. In the first year the two disagree by enough to move the same baby forty percentile points, with no change in the baby. Here is the size of the gap, and what the published thresholds for concern actually say.ExplainerHow Much Milk Does a Baby Need? The Rule of Thumb and Its LimitsA formula-fed baby takes roughly 2.3 fl oz per pound of body weight per day in the first months, split across the day's feeds. Here is the table by age and weight, why breastfed babies are not measured this way, and the signs that outrank any number.ExplainerWhere a Percentile Comes From: Which Population, Measured WhenA percentile is a rank against a reference population, so the first question is never the arithmetic — it is which population, measured when. The same 5'11" man is the 38th percentile in one national dataset and the 86th in another, and the 91st against a reference of people born a century ago. Here is why, and what a z-score adds.How-toHow to Find Your Target Weight for a Healthy BMIThe healthy BMI band of 18.5–24.9 turns into a weight range once you know your height. Here is how to work out yours step by step.