How does this calculator predict adult height?

It divides current standing height (cm) by an age- and sex-specific “fraction of mature height” interpolated between teaching knots. Example: boy age 8 at 128 cm → fraction ~0.765 → 128 ÷ 0.765 ≈ 167 cm adult point estimate, with a ±8 cm band (159–175 cm). Formula: predicted adult cm ≈ current cm ÷ fractionMatureHeight.

Is this as accurate as a bone age X-ray?

No. Bone age and Tanner puberty staging tell clinicians how much growth remains. A hand/wrist film with Bayley-Pinneau or similar methods can refine predictions in specialty care. This page uses population-average fractions only—fine for curiosity, inadequate for growth-hormone treatment decisions.

What is mid-parental height and how is it calculated?

Tanner-Davies target: boys (mother cm + father cm + 13) ÷ 2; girls (mother cm + father cm − 13) ÷ 2. Demo parents 165 & 182 cm for a son → (165+182+13)/2 = 180 cm genetic target. Compare with the current-height projection (~167 cm in the default demo)—a gap may prompt chart review, not alarm from one website snapshot.

Why does the calculator only work from age 2 to 17?

Under ~2 years, measurement technique (lying length vs standing) and infant growth velocity make simple adult-height multipliers unreliable. After ~17–18, most teens are near mature height—division by fractions near 1.0 adds little. Use CDC/WHO length-for-age and stature-for-age charts for infants and toddlers.

Why is there an ±8 cm uncertainty band?

Final adult height varies with puberty timing, nutrition, sleep, chronic disease, and polygenic inheritance beyond parental heights. ±8 cm is a teaching shorthand—not a 95% confidence interval from a validated prediction study. Reporting 167.3 cm alone falsely implies millimeter precision.

Should I use corrected age for a premature baby or toddler?

Many NICU follow-up programs plot corrected age until 2–3 years for interpreting early growth. This calculator does not auto-adjust for prematurity—enter the age your pediatrician uses on official charts, or ask your team before interpreting a number.

Does the “double your height at age 2” rule work?

It is a folk shortcut with variable accuracy across eras and populations. Standing height on a calibrated stadiometer, plotted on official growth charts, and tracked velocity (cm/year) outperform rules of thumb for medical follow-up.

My child is much taller than both parents—is that abnormal?

Not necessarily. Polygenic height inheritance allows regression toward or away from parental midpoints. Concern rises when stature is discordant with velocity, puberty timing, or associated symptoms (e.g., Marfan features, early puberty)—discuss with your pediatrician, not only an online projection.

Can teenagers still grow after the curve shows ~98% mature height?

Yes, especially late-maturing boys who may gain centimeters into the late teens. At age 16 and 175 cm, a boy’s fraction ~0.985 predicts ~178 cm—but individual bone age may still allow more. Clinicians integrate Tanner stage and growth velocity.

Girl age 12 at 152 cm—what might this tool show?

Fraction ~0.925 → 152 ÷ 0.925 ≈ 164 cm projected adult height (±8 cm → roughly 156–172 cm band). With parents 160 & 175 cm, mid-parental target ≈ (160+175−13)/2 = 161 cm—close agreement in this example; still plot CDC stature-for-age at well visits.

What units should I use?

Enter height in centimeters for precision. The form also displays feet and inches conversions. Parent heights should use the same cm units (measure without shoes, stadiometer when possible).

Is this medical advice?

No. It is educational. Pathologic short stature workup (Turner syndrome, celiac disease, growth hormone deficiency, hypothyroidism) requires examination, labs, imaging, and growth-chart trends from a pediatrician or pediatric endocrinologist.

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Growth & pediatrics

Child Height Prediction Calculator

Estimate a rough adult height band from your child's sex, age (about 2–17 years), and current standing height in centimeters. Uses interpolated fraction-of-mature-height curves plus an optional Tanner-Davies mid-parental target when both parents' heights are entered. Not bone age, not LMS chart inversion—pair with CDC growth charts at well-child visits.

Last updated: June 4, 2026

Sex-specific mature-height fractions (2–17 y)

±8 cm teaching band around point estimate

Optional mid-parental height comparison

Child height prediction

Projected adult height from current stature and age (≥2 y), with optional parental target—education only.

Sex (for growth curve)

Chronological age (years)

Model starts at about 2 years; use corrected age for preemies if advised.

Current standing height (cm)

Current value: 4 ft 2 in

Mother height (cm, optional)

Father height (cm, optional)

Projected adult height (from current height ÷ mature fraction)

159.3–175.3 cm

Midpoint ≈ 167.3 cm (5 ft 6 in)

Assumed fraction of adult height at this age/sex: 0.765

Mid-parental target (Tanner-Davies)

≈ 180 cm (5 ft 11 in)

Compare to the projection above; both are estimates with overlapping error.

Bone age X-rays, pubertal stage, chronic disease, nutrition, sleep, and genetics all shift final height—this page uses a simplified height-age multiplier only.
Growth charts (stature-for-age percentiles) remain the standard way your pediatrician tracks progress.
The ±8 cm band is a teaching convenience, not a statistically calibrated prediction interval.
Mid-parental target height compares your child’s genetic expectation from parental heights to the current-height projection—large gaps can prompt growth evaluation but are not diagnostic alone.

Example projections (this model)

Boy, 8 y, 128 cm (default)

~167.3 cm

159.3–175.3 cm band

Mid-parental target (parents 165 & 182 cm)

~180 cm

Tanner-Davies genetic line

Girl, 12 y, 152 cm

~164.3 cm

MPH target ~161 cm

Boy, 16 y, 175 cm

~177.7 cm

Fraction ~0.985 (near mature)

Fraction of mature height by age (teaching knots)

Linear interpolation between ages. Predicted adult height ≈ current height ÷ fraction.

Boys

Age (y)	Fraction
2	0.53
4	0.61
6	0.69
8	0.765
10	0.835
12	0.9
14	0.96
16	0.985
18	1

Girls

Age (y)	Fraction
2	0.54
4	0.635
6	0.72
8	0.79
10	0.86
12	0.925
14	0.975
16	0.992
18	1

Prediction methods compared

Method	Inputs	Output	Limitation
Current height ÷ mature fraction (this tool)	Sex, age 2–17, standing height cm	Point adult height + ±8 cm band	Ignores bone age, puberty stage, ethnicity-specific charts
Mid-parental height (Tanner-Davies)	Mother and father heights	Genetic target: (M+F±13)/2 by sex	Wide population spread; child may track above/below
CDC/WHO growth charts	Repeated height vs age	Percentile tracks and velocity	Gold standard for pediatrics—not a single adult cm guess
Bone age × Bayley-Pinneau	Hand/wrist X-ray maturity	Clinic-based adult height estimate	Requires radiology and specialist interpretation
“Double height at age 2” folk rule	Height at ~2 years	Rough guess only	Poor accuracy vs stadiometer + charts in many cohorts

When to discuss growth with a pediatrician

Height percentile crossing down over time (e.g., from 50th toward 5th)
Growth velocity clearly below expected for age/sex
Projected height far below mid-parental target with no family explanation
Delayed or absent puberty with short stature past expected timing
Chronic illness, celiac, hypothyroidism, or Turner syndrome concerns on exam

Worked example: default demo (boy, 8 y, 128 cm)

Parents 165 cm & 182 cm

Fraction at age 8 (male) ≈ 0.765

128 ÷ 0.765 ≈ 167.3 cm (5 ft 6 in)

Band: 159.3–175.3 cm (±8 cm teaching margin)

Mid-parental: (165 + 182 + 13) ÷ 2 = 180 cm — compare projection vs genetic target over time on growth charts.

Worked example: younger child (girl, 4 y, 102 cm)

Higher uncertainty—fraction still low

Fraction ~0.635 → 102 ÷ 0.635 ≈ 160.6 cm adult projection

Early childhood projections swing more with measurement error and nutrition spurts—rely on plotted percentiles more than a single adult cm number.

References

CDC Growth Charts — stature-for-age
WHO Child Growth Standards — length/height for young children
Tanner JM — Use of parental data in predicting adult height (mid-parental height method)

Education only. Not for growth hormone prescribing, skeletal maturity assessment, or diagnosing short stature. Use your pediatrician's growth charts and specialist referral when indicated.

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Growth & pediatrics

Child Height Prediction Calculator

Last updated: June 4, 2026

Sex-specific mature-height fractions (2–17 y)

±8 cm teaching band around point estimate

Optional mid-parental height comparison

Child height prediction

Projected adult height from current stature and age (≥2 y), with optional parental target—education only.

Sex (for growth curve)

Chronological age (years)

Model starts at about 2 years; use corrected age for preemies if advised.

Current standing height (cm)

Current value: 4 ft 2 in

Mother height (cm, optional)

Father height (cm, optional)

Projected adult height (from current height ÷ mature fraction)

159.3–175.3 cm

Midpoint ≈ 167.3 cm (5 ft 6 in)

Assumed fraction of adult height at this age/sex: 0.765

Mid-parental target (Tanner-Davies)

≈ 180 cm (5 ft 11 in)

Compare to the projection above; both are estimates with overlapping error.

Bone age X-rays, pubertal stage, chronic disease, nutrition, sleep, and genetics all shift final height—this page uses a simplified height-age multiplier only.
Growth charts (stature-for-age percentiles) remain the standard way your pediatrician tracks progress.
The ±8 cm band is a teaching convenience, not a statistically calibrated prediction interval.
Mid-parental target height compares your child’s genetic expectation from parental heights to the current-height projection—large gaps can prompt growth evaluation but are not diagnostic alone.

Example projections (this model)

Boy, 8 y, 128 cm (default)

~167.3 cm

159.3–175.3 cm band

Mid-parental target (parents 165 & 182 cm)

~180 cm

Tanner-Davies genetic line

Girl, 12 y, 152 cm

~164.3 cm

MPH target ~161 cm

Boy, 16 y, 175 cm

~177.7 cm

Fraction ~0.985 (near mature)

Fraction of mature height by age (teaching knots)

Linear interpolation between ages. Predicted adult height ≈ current height ÷ fraction.

Boys

Age (y)	Fraction
2	0.53
4	0.61
6	0.69
8	0.765
10	0.835
12	0.9
14	0.96
16	0.985
18	1

Girls

Age (y)	Fraction
2	0.54
4	0.635
6	0.72
8	0.79
10	0.86
12	0.925
14	0.975
16	0.992
18	1

Prediction methods compared

Method	Inputs	Output	Limitation
Current height ÷ mature fraction (this tool)	Sex, age 2–17, standing height cm	Point adult height + ±8 cm band	Ignores bone age, puberty stage, ethnicity-specific charts
Mid-parental height (Tanner-Davies)	Mother and father heights	Genetic target: (M+F±13)/2 by sex	Wide population spread; child may track above/below
CDC/WHO growth charts	Repeated height vs age	Percentile tracks and velocity	Gold standard for pediatrics—not a single adult cm guess
Bone age × Bayley-Pinneau	Hand/wrist X-ray maturity	Clinic-based adult height estimate	Requires radiology and specialist interpretation
“Double height at age 2” folk rule	Height at ~2 years	Rough guess only	Poor accuracy vs stadiometer + charts in many cohorts

When to discuss growth with a pediatrician

Height percentile crossing down over time (e.g., from 50th toward 5th)
Growth velocity clearly below expected for age/sex
Projected height far below mid-parental target with no family explanation
Delayed or absent puberty with short stature past expected timing
Chronic illness, celiac, hypothyroidism, or Turner syndrome concerns on exam

Worked example: default demo (boy, 8 y, 128 cm)

Parents 165 cm & 182 cm

Fraction at age 8 (male) ≈ 0.765

128 ÷ 0.765 ≈ 167.3 cm (5 ft 6 in)

Band: 159.3–175.3 cm (±8 cm teaching margin)

Mid-parental: (165 + 182 + 13) ÷ 2 = 180 cm — compare projection vs genetic target over time on growth charts.

Worked example: younger child (girl, 4 y, 102 cm)

Higher uncertainty—fraction still low

Fraction ~0.635 → 102 ÷ 0.635 ≈ 160.6 cm adult projection

Early childhood projections swing more with measurement error and nutrition spurts—rely on plotted percentiles more than a single adult cm number.

References

CDC Growth Charts — stature-for-age
WHO Child Growth Standards — length/height for young children
Tanner JM — Use of parental data in predicting adult height (mid-parental height method)

Education only. Not for growth hormone prescribing, skeletal maturity assessment, or diagnosing short stature. Use your pediatrician's growth charts and specialist referral when indicated.