Projected Adult Height Calculator

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Growth corridor visual unavailable

Mother height:

Changing this unit converts the displayed quantity without changing the physical height.

Father height:

Use a measured adult height when available rather than a remembered or rounded value.

Child formula sex:

Choose the sex-specific growth-reference path recorded for this calculation.

Child age:

Enter completed years plus months from age 2 through 17.

years months

Current standing height:

Measure without shoes; changing the unit preserves the physical height.

Reference sensitivity:

Keep Hybrid for continuity; use the other lenses only to test sensitivity.

Projection method:

The blended mode is a planning heuristic; none of these paths is a clinical prediction.

Family target band:

Choose 4–15 cm; the default half-width is 8.5 cm.

Current weight:

Set 0 to omit BMI context; changing the unit preserves the physical weight.

Percentile blend override:

{{ formatNumber(projection_blend_override_percent, 0) }}%

Optional 0–100%; default 0 keeps automatic blending.

Puberty timing offset:

Optional −24 to +24 months; default 0 leaves the age anchor unchanged.

Review interval:

Choose 0.5–12 months for the planning reminder.

months

Review urgency:

Routine preserves the chosen interval; Priority and Urgent shorten the planning reminder.

Projection wording:

This affects interpretation wording only; the numeric result remains unchanged.

Measure	Current result	Meaning	Copy
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Scenario	Adult-height midpoint	Difference	Use	Copy
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Review point	Current evidence	Best use	Copy
{{ row.label }}	{{ row.evidence }}	{{ row.use }}

Next step	Timing	Why it matters	Copy
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Adult height cannot be read from one childhood measurement with certainty. Inherited stature, the child's current growth pattern, puberty timing, nutrition, illness, medicines, and measurement quality all affect the eventual outcome. A projection is most useful as a broad planning range that can be checked against later measurements, not as a promised final height.

Two clues are commonly used. A family target estimates the center of the range suggested by the parents' measured heights. A stature-for-age position compares the child with a reference population of the same age and sex. These clues can agree closely, or they can point to different endpoints when a child is temporarily growing earlier, later, faster, or slower than the reference pattern.

Family target: A rough midpoint derived from both parents' adult heights with a sex-specific adjustment.
Current position: An approximate stature-for-age percentile based on one standing-height measurement.
Projection range: An uncertainty envelope around the selected midpoint. It should stay attached whenever the estimate is discussed.
Scenario spread: The distance between alternate projection assumptions. A wide spread signals that the midpoint depends heavily on the chosen method.

Growth charts describe how measurements compare with a reference population; they do not diagnose a cause or predict one child's future by themselves. A percentile is also not a grade. A child may be healthy near either end of the chart, while crossing percentiles over time can deserve more attention than a single low or high reading.

Standing height should be measured without shoes on a level surface, with the head positioned consistently and the result dated. A second reliable measurement adds more information than extra decimal places because growth velocity requires change over time. Puberty history and bone age can materially alter clinical height prediction, but neither is established by a slider or a single stature entry.

This estimate is educational and is not official CDC or WHO chart output, a diagnosis, or a substitute for pediatric assessment. Rapid percentile crossing, unusual puberty timing, chronic illness, medication concerns, or persistent worry should be reviewed by a qualified clinician.

How to Use This Tool:

Begin with measured family and child stature, then use the alternate scenarios to judge how much the estimate depends on its assumptions.

Enter Mother height and Father height. Choose cm or in for each value; changing the unit converts the displayed number without changing the physical height.
Choose Child formula sex, then enter completed years, months, and Current standing height. The accepted age range is 2 years through 17 years.
Keep Reference sensitivity on the hybrid setting for a continuity check, or compare the WHO-leaning and CDC-leaning approximations as sensitivity tests. They are compact internal approximations, not official chart calculations.
Choose a Projection method. The blended method combines the family target and current-position comparator; the other methods isolate either the percentile-tracking or family-anchor view.
Use the advanced blend and puberty-timing controls only to test sensitivity. A nonzero blend override replaces the automatic weight, and the timing offset shifts that automatic weight and the uncertainty range.
A timing offset is not a puberty assessment. Use it to see how the planning estimate moves under a different assumption.
Read Projection range and Scenario spread with the midpoint. If the input warning appears, correct the listed age, height, unit, or advanced value before interpreting any result.

Interpreting Results:

The midpoint is a planning estimate. Keep the displayed low-to-high range beside it, and give extra weight to Scenario spread when the percentile and family clues disagree. A spread of 4 cm or less is labeled stable across nearby scenarios, more than 4 cm through 8 cm is moderately sensitive, and more than 8 cm is highly assumption-sensitive.

Family-band fit compares the selected projection with the chosen half-width around the family target. Being outside that band is a prompt to check measurements and growth history, not proof of a growth disorder. The approximate current-position labels use strict cutoffs below the 3rd and 10th percentiles and above the 90th and 97th percentiles.

Optional BMI is context only and never changes the height projection. For a child or teenager, BMI must be interpreted for age and sex rather than as an adult BMI category.

Technical Details:

The model combines a rough mid-parental target with a current-position comparator. It first estimates a z-score from age- and sex-specific height anchors, carries that standardized position to an adult reference, and then blends that endpoint with the family target. The reference anchors and uncertainty envelope are repository-authored approximations.

Formula Core

The family target uses the measured parental heights in centimetres. The 13 cm adjustment is added for the boy formula and subtracted for the girl formula before division by two.

F_{boy} = \frac{M + P + 13}{2} F_{girl} = \frac{M + P - 13}{2}

Current standing height is standardized against the selected age reference, then transferred to the adult median and standard deviation for the selected sex.

z = \frac{H - m_{age}}{s_{age}} T = m_{adult} + z s_{adult}

The selected midpoint is a weighted average of the percentile-tracking endpoint and family target.

A = w T + (1 - w) F

Projected adult height formula symbols
Symbol	Meaning	Unit
`M`, `P`	Mother and father adult height	cm
`H`	Current child standing height	cm
`m`, `s`	Reference median and standard deviation at the named age or adult endpoint	cm
`T`	Percentile-tracking comparator	cm
`F`	Mid-parental family target	cm
`w`	Percentile weight in the blend	ratio from 0 to 1
`A`	Selected projected adult-height midpoint	cm

Weighting and Uncertainty Rules

The automatic percentile weight is the age in months plus the timing offset, divided by 180 and limited to 0.35 through 0.90. Percentile-tracking forces a weight of 1. The family-anchor method uses 0.35 unless a nonzero manual override is present; any override supplies the weight directly as a percentage.

The range half-width starts with 8.4 minus adjusted age divided by 54. It then adds up to 2.5 cm for disagreement between the two endpoints, up to 1.8 cm for the absolute timing offset, and 0.4 cm when a manual blend is used. The final half-width is limited to 3.5 through 9.8 cm. Results retain four decimal places internally and are normally shown to one decimal place.

Family-band membership is inclusive at both edges. A projection is below only when it is strictly less than the family target minus the selected band, and above only when it is strictly greater than the target plus the band.

Accuracy Notes:

The CDC-leaning, WHO-leaning, and hybrid choices are sensitivity lenses built from compact anchor tables. They do not reproduce official LMS chart calculations, account for ethnicity or region, use bone age, or model an individual's puberty stage.

A single height cannot establish growth velocity; compare reliable dated measurements.
Remembered or rounded parental heights can move the family target.
The displayed range is a model envelope, not a confidence interval from a validated clinical prediction study.
Clinical interpretation may require growth records, examination, family history, bone age, or laboratory testing.

Worked Examples:

Family and current-position clues agree

For a 10-year-old girl who is 138 cm tall, with parental heights of 162 cm and 176 cm, the hybrid blended setting produces a family target of 162.5 cm and a percentile comparator of 164.5 cm. The selected midpoint is about 163.8 cm, with a displayed range of about 157.4 to 170.3 cm. The nearby scenarios span only 1.3 cm, so the assumptions agree reasonably well, but the range still belongs with the midpoint.

References:

Predicting a Child's Adult Height, American Academy of Pediatrics, updated June 8, 2015.
CDC Growth Charts Data Files, Centers for Disease Control and Prevention.
Growth reference data for 5 to 19 years, World Health Organization.