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Child Parent band Projection {{ projectionHeightStage.methodLabel }}
Pick cm, inches, or ft/in first; switching later keeps child height in cm internally.
Examples: 162 cm, 64 in, or 5 ft 4 in; use biological adult standing height when known.
ft in
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Examples: 176 cm, 69.3 in, or 5 ft 9 in; use biological adult standing height when known.
ft in
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Choose Girl or Boy to match the reference profile used for height percentile and adult context.
Use completed years plus 0-11 months; total age must be 2y 0m through 17y 0m.
years months
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Use a recent standing height, for example 138 cm or 4 ft 6.3 in.
ft in
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Hybrid is default; use WHO-style or CDC-style only when you want that reference lens.
Blended is baseline; compare Percentile tracking only or Family-target anchor for sensitivity.
Enter 4-15 cm; 8.5 cm is the standard default half-width.
cm
Optional; enter kg from the same visit as height, or leave blank/0 to omit BMI context.
kg
Enter 0-100%; 0 keeps the automatic age-based blend.
%
Enter -24 to 24 months; negative means earlier timing, positive means later.
months
Enter 0.5-12 months in half-month steps; default is 3 months.
months
Routine keeps baseline timing; Priority and Urgent shorten suggested review windows.
Choose Cautious, Balanced, or Optimistic for how strongly guidance qualifies the estimate.
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Scenario Projected adult height Delta vs baseline Family band fit What changed Copy
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Signal Current reading How to read it Best use Copy
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Tags: Body Metrics, Diagnostics, Education
Growth Screening Flag Checker Check child growth visits for percentile drift, corrected age, height velocity, adiposity, and family-height flags with triage guidance.
Growth Velocity Calculator Calculate child growth velocity from height or weight visit rows, with expected bands, percentile drift, spacing confidence, and follow-up cues.
Height-for-Age Percentile Calculator Calculate a child's height-for-age percentile from age, sex, and length or stature, with z-score, WHO/CDC comparison, and screen margins.
Mid-Parental Target Height Calculator Estimate a child's mid-parental target height from parent heights, compare classic and adjusted methods, and review family bands with growth cautions.
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A child's future adult height is usually discussed as a range because growth is a moving pattern, not a single event. One measurement tells where the child stands today. A growth chart shows how that height compares with children of the same age and sex. Parent heights add a family-height clue. The useful estimate comes from reading those clues together while keeping measurement error, puberty timing, and health history in view.

Height percentile is a comparison rank, not a grade. A child near the 50th percentile is close to the middle of the reference group for that age and sex. A child near the 5th or 95th percentile is farther from the middle, but that can still be normal when the child's family pattern fits. The concern rises when the percentile is very low or very high, shifts sharply over time, or conflicts strongly with biological parent heights.

Clue What it adds Common mistake
Current standing height Places the child on an age-and-sex growth curve. Trusting one casual measurement as if it were exact.
Parent heights Gives a rough genetic target through mid-parental height. Expecting the child to land exactly at the family midpoint.
Age and puberty timing Changes how much growth may remain. Comparing early and late maturers as if they were at the same growth stage.
Growth history Shows whether the child is following a familiar pattern or crossing percentiles. Using a projection without checking prior measurements.

Mid-parental height is a simple family-height shortcut. It averages the two biological parent heights after applying a sex-specific adjustment, then treats the result as a rough target rather than a guaranteed endpoint. It helps separate a short child from a short family pattern, or a tall child from a tall family pattern, but it cannot account for bone age, chronic disease, nutrition, medications, hormone conditions, or the exact timing of the adolescent growth spurt.

Diagram linking current standing height, growth percentile lane, parent target, and projected adult range.

Adult-height estimates are most helpful for planning language, not for deciding that a child will become a precise number of centimeters tall. They can guide a conversation about whether today's height is broadly consistent with family background, whether a growth visit should be repeated soon, or whether a clinician should review possible early puberty, delayed puberty, nutrition, chronic illness, or endocrine causes.

A projected range should never replace a pediatric growth review when the child is below the expected family range, above it by a large amount, crossing percentiles, showing unusual puberty timing, or causing persistent family concern. In those cases, the next useful evidence is usually a reliable repeat measurement, a plotted growth record, and professional assessment rather than a more exact calculator result.

How to Use This Tool:

Start with the most reliable recent standing height, then compare the midpoint, range, and scenario rows before sharing the result.

  1. Choose Height unit first. The height fields accept centimeters, inches, or feet plus inches, and companion text helps you catch a unit mix-up before the projection updates.
  2. Enter Mother height and Father height as adult standing heights when known. Both values are needed for the Family target midpoint and Family target band.
  3. Select Child sex, then enter Child age from 2y 0m through 17y 0m and the child's Current height. If the age or height is outside the supported range, the red message names the value to fix.
  4. Use Growth reference set to choose the comparison lens. Hybrid continuity model is the default, while the WHO-style and CDC-style options let you test a different reference emphasis.
  5. Choose Projection method mode. The age-weighted blended model combines current percentile with the family target, Percentile tracking only removes the parental pull, and Family-target anchor gives the parent midpoint more influence.
  6. Set Family target band if you want a narrower or wider family-fit check. The page keeps this half-width between 4 and 15 cm, with 8.5 cm as the default.
  7. Open Advanced only when you need optional Current weight for BMI-for-age context, a Projection blend override, a Puberty timing offset, or different action-guide wording. Weight adds context but does not change the projected adult height.
  8. Read Projection Snapshot first, then compare Projection Scenarios, Interpretation Guide, Action Guide, and Projection Path Chart. If the scenario rows disagree, quote the range and the Scenario spread before the midpoint.

Interpreting Results:

The main result is the relationship between Blended projected adult height, Projected range, Current height percentile, Family target band, and Scenario spread. A midpoint inside the family band with a small scenario spread is easier to use for planning than a midpoint that changes several centimeters when the method or puberty timing changes.

Do not overread a one-decimal centimeter value. Recheck Current height, Child age, and parent heights if the result seems surprising, then look at Track vs family midpoint gap and Family band fit. A large gap means current stature and parent-height expectations are pulling the estimate in different directions.

  • Inside family target band means the projected midpoint is within the selected half-width around the mid-parental target.
  • Scenario spread near 4 cm or less is treated as stable; above 8 cm, the range matters more than the midpoint.
  • Current height percentile below the 3rd or at least the 97th percentile raises the review priority in the action guide.
  • BMI-for-age context, when present, describes body-size context only. It does not alter the height projection formula.

Technical Details:

Projected adult height combines a growth-chart position with a family-height target. The growth-chart side converts current standing height into a z-score, then applies that same standard-deviation position to an adult same-sex reference. The family side calculates a mid-parental target by averaging biological parent heights with a 13 cm sex adjustment.

The reference setting changes the internal median and spread used for the height percentile and optional BMI context. These lanes are simplified planning references, not official CDC or WHO growth-chart table output. The projection is deterministic for the entered values, but the clinical question remains uncertain because puberty timing, bone age, growth velocity, and health history are not fully captured by a single current height.

Formula Core:

The main equations use centimeters after any inch or feet-plus-inches entry has been converted.

z = Hcurrent-M(age,sex) SD(age,sex) Hpercentile = Madult+z×SDadult Hfamily = Hmother+Hfather±13 2 Hprojected = w×Hpercentile+(1-w)×Hfamily
Symbol Meaning Unit or source
z Current height expressed as standard deviations from the selected reference median. Unitless
Hpercentile Adult height from carrying today's height z-score to the adult same-sex reference. cm
Hfamily Mid-parental target. The 13 cm adjustment is added for boys and subtracted for girls. cm
w Percentile share of the blend. Automatic mode uses age in months divided by 180, clamped from 0.35 to 0.90. 0 to 1
BMI Optional body mass index, computed as weight divided by squared height in meters. kg/m2

Percentile-only mode sets the blend weight to 1. Family-target anchor mode uses a 0.35 percentile share unless a manual override is active. The puberty timing offset moves the age anchor by -24 to 24 months before the automatic blend is calculated, which changes both the midpoint and the uncertainty range.

Range width starts wider in younger children and narrows as the age anchor increases. It grows again when the percentile-based adult estimate disagrees with the family target, when a puberty offset is applied, or when a manual blend override is used. The displayed range half-width is clamped from 3.5 to 9.8 cm.

Check Boundary How it affects the result
Supported child age 24 to 204 months inclusive Outside this range, the page asks for a valid child age.
Current height 70 to 220 cm inclusive Values outside the range stop the projection and show a realistic-height error.
Parent heights Mother 120 to 220 cm, father 130 to 235 cm when entered Out-of-range parent heights stop the family-target calculation until corrected.
Family target band 4 to 15 cm half-width The family-fit label compares the projected midpoint with target minus band through target plus band.
Current percentile flag <3rd, 3rd to <10th, 10th to <90th, 90th to <97th, and >=97th Very low or very high percentiles increase the action-guide priority.
Scenario stability <=4 cm, <=8 cm, or >8 cm spread Higher spread means assumptions have more influence, so the range should be emphasized.

With the default example, a 10-year-old girl at 138 cm is close to the 50th percentile in the hybrid lane. Parent heights of 162 cm and 176 cm give a family target midpoint of 162.5 cm. The adult percentile path is about 164.5 cm, and the age-weighted blend lands near 163.8 cm with a projected range of about 157.4 to 170.2 cm.

The chart extends the current percentile path from the child's present age toward adulthood, adds a 50th-percentile reference, and marks the family target band plus current, earlier-timing, and later-timing endpoints. Table and chart values keep more precision during calculation, while most displayed heights round to one decimal place.

Accuracy Notes:

This is an informational growth estimate, not medical advice, diagnosis, or treatment guidance. It cannot replace a pediatric growth chart review, repeated accurate measurements, pubertal staging, bone-age assessment, or clinician judgment.

  • Use standing height measured without shoes, preferably from a recent growth visit.
  • Repeat the estimate after reliable new measurements instead of relying on one casual height entry.
  • Seek professional review for very low or very high percentiles, rapid percentile crossing, delayed puberty, early puberty, chronic illness, or persistent concern.

Worked Examples:

Typical school-age estimate. A 10-year-old girl is 138 cm, with parent heights of 162 cm and 176 cm. Projection Snapshot reports a current height percentile near the 50th, a Family target midpoint near 162.5 cm, and Blended projected adult height near 163.8 cm. Because Scenario spread is about 1.3 cm, the midpoint and range are close across the default comparison scenarios.

Family target pulls upward. A 13-year-old boy at 160 cm with parent heights of 165 cm and 180 cm has a Percentile-tracking adult estimate near 173.1 cm and a Family target midpoint near 179.0 cm. The blended result is about 173.9 cm, while Family-target anchor is closer to 176.9 cm. That Track vs family midpoint gap should be discussed before quoting one future height.

Input needs review. If a child age is entered as 18 years, Child age is outside the 24 to 204 month range and the page shows a validation message. If current height is typed as 22 cm instead of 122 cm, Current height fails the realistic-height check. Fix the unit or number first, then confirm that Current height percentile looks believable.

FAQ:

Why does the estimate show a range?

Adult height depends on measurement quality, growth timing, and how closely the current percentile agrees with the family target. The Projected range keeps that uncertainty visible.

What if I do not know both parent heights?

The Family target midpoint becomes unavailable, so the estimate relies on percentile tracking. The result can still be useful, but Family band fit cannot judge whether the endpoint matches parent-height background.

Does current weight change projected adult height?

No. Current weight only adds BMI-for-age context. It does not change the height percentile, family target, blended midpoint, projected range, or scenarios.

Why do puberty timing settings move the result?

The Puberty timing offset shifts the age anchor used in the blend and range logic. Earlier or later timing can change how much the current percentile influences the projected endpoint.

Why did I get a realistic-range error?

The page checks child age, current height, parent heights, and optional weight against broad supported ranges. Recheck centimeters versus inches or feet plus inches first, then correct the field named in the red message.

Glossary:

Height percentile
A comparison rank against children of the same age and sex in the selected reference lane.
z-score
The number of standard deviations a child's height sits above or below the selected median.
Mid-parental target
A rough family-height midpoint calculated from biological parent heights with a sex-specific 13 cm adjustment.
Scenario spread
The distance between alternate adult-height endpoints created by method and puberty-timing assumptions.
BMI-for-age
Body mass index interpreted by age and sex; here it is optional context, not a direct adult-height predictor.

References: