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Visit rail unavailable. Review the visit rows and interval table.

Use the reference curve that matches the clinical growth record.
Choose height or weight and the unit used by every visit row.
One age_months,value pair per line. Use 2–20 visits from 0–240 months.
Hybrid follows the common WHO-to-CDC handoff at 24 months; verify the actual chart used by the record.
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Auto uses each interval midpoint; fixed profiles apply one stage multiplier to every interval.
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Choose 0.80–1.20; 1.00 keeps the preserved baseline.
Choose how many consecutive low or high intervals trigger the sustained-pattern badge.
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IntervalObservedExpected bandPercentile driftSpacingStatusCopy
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Chart unavailable. Review the table or download the chart data as CSV.

Chart unavailable. Review the table or download the chart data as CSV.

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Growth Percentile Trend Calculator Review a child's height, weight or BMI percentile path across visits with WHO/CDC references plus band-crossing alerts and trend context.
Growth Screening Flag Checker Screen serial child growth measurements for percentile drift and low height velocity, with age-routed adiposity checks and data-quality flags.
Growth Z-Score Calculator Place a child's height, weight or BMI on age- and sex-specific WHO or CDC curves with z-score, percentile and reference-gate context.
Body Metrics Calculator Compare adult BMI and waist ratios with three body-fat estimates, derived fat and lean mass plus BSA and method-spread warnings.

Growth is a pattern across time, not a verdict from one measurement. A child's height or weight can move because of normal development, puberty, illness, nutrition, hydration, measurement technique, or a change from lying length to standing height. Serial measurements reveal whether a change persists and whether the intervals are long enough to interpret.

Growth velocity annualizes the change between two visits. Twelve centimetres gained over twelve months is 12 cm/year; the same gain over six months annualizes to 24 cm/year. Annualization makes intervals comparable, but it also magnifies small measurement errors when visits are close together.

Percentile position and velocity answer related but different questions. A percentile compares attained size with a reference population at one age. Velocity describes the pace between ages. A child may stay at a low percentile while growing steadily, cross percentiles during a normal transition, or remain inside a broad percentile range while the latest pace warrants remeasurement.

  • Use the same measurement method and equipment whenever possible.
  • Check age, units, and whether length or standing height was recorded.
  • Give more weight to a consistent series than to one short or unusual interval.
  • Interpret chart changes with medical, developmental, and family context.

These comparisons are an informational screen, not a clinical growth chart, diagnosis, or treatment recommendation. The expected rates, reference anchors, confidence score, and alert rules are repo-authored heuristics. A pediatric clinician should assess concerning measurements, sustained slowing or acceleration, symptoms, or questions about a child's growth.

How to Use This Tool:

Prepare at least two measurements taken at different ages, using one metric and one unit throughout the series.

  1. Choose the reference sex, Height or Weight, and the unit used by every visit row.
  2. Enter one age-in-months and measurement pair per line. Use 2 to 20 unique visit ages from 0 to 240 months; when an age is repeated, only the last row at that age is retained.
  3. Select the reference context and expected-growth stage. The hybrid context follows the WHO-to-CDC handoff at 24 months, while a fixed stage applies one multiplier to every interval.
  4. Review the Interval review before the summary badge. Check spacing, observed velocity, comparison band, percentile shift, and any repeated low or high pattern.

Interpreting Results:

Low, Expected, and High compare an interval with the selected heuristic band. They are not clinical classifications. The Review confidence score reflects visit count, total span, and spacing quality within this model; it does not measure diagnostic certainty.

  • Remeasure an unexpected short interval before treating the annualized rate as a trend.
  • Read percentile drift alongside the observed measurements. Switching from WHO to CDC charts at 24 months can change the plotted percentile without an abrupt biological change.
  • A sustained-pattern badge requires the selected number of consecutive low or high intervals. It is a prompt for review, not proof of a disorder.
  • Seek clinical advice when measurements repeatedly slow or accelerate, cross major chart bands, conflict with the child's health or development, or appear technically unreliable.

Technical Details:

Measurements are converted to centimetres for height and kilograms for weight. Visits are sorted by age. Every adjacent pair becomes one interval, and the interval midpoint selects the expected age rate when automatic stage selection is active.

Formula Core:

For measurements M1 and M2 separated by Δm months, annualized velocity V is:

V=(M2−M1)12Δm

The expected centre E multiplies an age-based base rate B by the selected stage factor S. Sensitivity s then sets the lower and upper comparisons.

E=BS,Vlow=E[0.7+0.08(s−1)],Vhigh=E[1.4−0.12(s−1)]

An observed velocity below the lower bound is Low; above the upper bound is High. Equality with either bound remains Expected. Sensitivity ranges from 0.80 to 1.20. At 1.00, the band is 70% through 140% of the expected centre.

Midpoint ageHeight baseWeight base
0 to under 12 months24 cm/year6 kg/year
12 to under 24 months12 cm/year3 kg/year
24 to under 36 months8 cm/year2.2 kg/year
36 to under 60 months7 cm/year2.2 kg/year
60 to under 120 months5.5 cm/year2.6 kg/year
120 to under 156 months5 cm/year3.4 kg/year
156 to under 180 months7.5 cm/year4.8 kg/year
180 to under 204 months4 cm/year3 kg/year
204 to 240 months2.2 cm/year1.7 kg/year

Automatic stages multiply those base rates by 1.18 before 12 months, 1.05 from 12 to under 36 months, 0.92 from 36 to under 120 months, and 0.82 from 120 months onward. A fixed stage uses its multiplier for every interval, regardless of age.

Rule Core:

The percentile path is also heuristic. Sex-specific height and weight medians are linearly interpolated between repo-authored age anchors. Height spread is interpolated from age anchors; weight spread is the larger of 0.45 kg or 12% of the median plus 0.3 kg. WHO and CDC choices apply small age- and metric-specific factors to those medians and spreads; they do not load official chart tables.

A z-score is converted through an approximate normal distribution and bounded to 0.1 through 99.9 percentile. Major-band crossings count movement across the 3rd, 15th, 50th, 85th, and 97th percentile boundaries.

z=Mobserved−Mmedianσreference
Interval spacingLabelScore
Under 3 monthsToo short0.45
3 to under 6 monthsUsable short0.72
6 through 12 monthsPreferred1.00
Over 12 through 18 monthsExtended0.70
Over 18 monthsLong gap0.50

Review confidence is bounded from 20 to 95. It starts at 30, adds up to 40 points for as many as four intervals, up to 15 points for a span reaching 24 months, and up to 30 points from the mean spacing score. Six points are removed for each interval under 3 months or over 18 months.

For height only, an additional floor is flagged at interval midpoints from 24 to under 120 months: 5.5 cm/year before 48 months, 5 cm/year before 72 months, then 4 cm/year for males or 4.5 cm/year for females. These floors and all pattern labels are part of the repo-authored screen, not WHO or CDC diagnostic cutoffs.

Accuracy and Privacy Notes:

Measurement quality can dominate the calculated change, especially over short intervals. CDC guidance stresses accurate measurement, correct age, the appropriate chart, and a series of observations over time.

  • WHO charts are commonly used from birth to 2 years in U.S. clinical settings, followed by CDC charts from age 2 through 20. The transition can change percentile classification.
  • The available reference contexts approximate that distinction with repo-authored anchors and adjustment factors; they are not official WHO or CDC chart calculations.
  • Entered visit rows are processed in the browser and no server lookup is used. Avoid putting identifiable child information in the optional scenario data you copy or share elsewhere.

Worked Examples:

A twelve-month height interval

A female height series of 74 cm at 12 months and 86 cm at 24 months gains 12 cm over one year, so the observed velocity is 12 cm/year. With automatic stage selection and sensitivity 1.00, the accepted reference case gives an expected centre of 12.6 cm/year and a comparison band from 8.82 to 17.64 cm/year. The interval is labelled Expected, but that label does not replace plotting the actual clinical record.

Why a short interval needs care

A 0.5 cm measurement difference over one month annualizes to 6 cm/year. A small posture or equipment error can therefore change the apparent rate substantially. Repeating the measurement and waiting for an appropriate clinical interval gives stronger evidence than adjusting the alert sensitivity.

References: