What is mid-parental height (target height)?

Mid-parental height—also called target height or genetic height potential—is the adult stature pediatricians expect a child to reach based on the heights of both biological parents. It does not use the child's current height. Clinicians plot this endpoint on CDC stature-for-age charts at age 18–20 and compare it to the child's growth percentile curve. If the curve would land near the target, growth is considered consistent with family genetics.

How do you calculate mid-parental height step by step?

Tanner-Davies (metric): Boys → (mother cm + father cm + 13) ÷ 2. Girls → (mother cm + father cm − 13) ÷ 2. Imperial equivalent: boys add 5 in, girls subtract 5 in before dividing by 2. Example with mother 163 cm and father 178 cm for a son: (163 + 178 + 13) ÷ 2 = 177 cm (~5 ft 10 in). For a daughter with the same parents: (163 + 178 − 13) ÷ 2 = 164 cm (~5 ft 5 in). The ±13 cm (±5 in) term reflects the average adult sex difference in stature.

How accurate is mid-parental height for predicting adult height?

It is a population-based genetic estimate, not a precision forecast. Teaching literature states that roughly 95% of children finish within ±4 inches (±10 cm) of the calculated target. Individual variation from polygenic inheritance, puberty timing, nutrition, chronic disease, and skeletal maturity can push final height outside that band. Bone age methods and repeated growth-chart velocity outperform a one-time parental-height calculation for clinical decisions.

Why do boys add 13 cm and girls subtract 13 cm?

The adjustment centers the child's expected adult height within the sex-specific population distribution. Adult men average about 13 cm (5 in) taller than adult women globally; adding 13 cm for boys and subtracting 13 cm for girls shifts the parental average toward the sex-appropriate mature stature. Without this step, boys would be underestimated and girls overestimated.

What is the 95% confidence interval shown in the results?

The calculator displays target height ±4 in (±10 cm)—a clinical teaching range, not a statistically calibrated prediction interval from a single study. Pediatric endocrinology references cite that most children's final adult height falls within this margin of mid-parental height. A boy with target 177 cm would have a teaching span of roughly 167–187 cm. Outliers still occur; chart trends matter more than one snapshot.

At what age should I calculate mid-parental height?

You can compute it before birth because it depends only on parental genetics. Pediatricians typically begin comparing target height to measured growth percentiles after age 2, when standing height on a stadiometer is reliable. Before age 2, use WHO length-for-age or CDC growth charts rather than adult-height formulas. For school-age children, pair this genetic target with our child height prediction tool that uses current stature.

How do pediatricians use mid-parental height on growth charts?

At well-child visits, clinicians plot height-for-age percentiles and mark the mid-parental target at the adult end of the chart (around 18–20 years). Healthy growth often follows a percentile line that intersects that target. If a child at the 25th percentile has parents whose target is at the 75th percentile, the doctor watches whether velocity accelerates during puberty. A downward percentile crossing with a projected finish far below target may trigger labs (thyroid, celiac screen) or endocrine referral.

What else affects final height besides genetics?

Nutrition (calories, protein, vitamin D), chronic illnesses (celiac disease, inflammatory bowel disease, heart disease), untreated hypothyroidism, growth hormone deficiency, Turner syndrome in girls, glucocorticoid exposure, sleep deprivation, and severe psychosocial stress can limit stature. Conversely, early puberty or constitutional tall stature may produce an adult height above the genetic target. Genetics set the ceiling; environment and health determine how close a child gets.

What if one parent is much taller than the other?

The formula averages both parents, so extreme discordance yields a midpoint target. Children may track closer to one parent's stature pattern due to which alleles they inherit—polygenic height is not a simple 50/50 blend. Example: father 193 cm, mother 160 cm → boy target ≈ (160 + 193 + 13) ÷ 2 = 183 cm. Some sons finish nearer 193 cm, others nearer 170 cm; the ±10 cm band captures much of that spread.

Is mid-parental height the same as a bone age prediction?

No. Bone age assessment uses a left-hand/wrist X-ray to grade skeletal maturity, then applies tables such as Bayley-Pinneau to estimate remaining growth. That method integrates how much growth is left—not just family height. Mid-parental height is simpler, requires no imaging, and is useful for genetic benchmarking. Endocrinologists combine bone age, pubertal stage (Tanner), growth velocity, and mid-parental height for short-stature workups.

Can my child be taller than the calculated target?

Yes. Regression toward or away from the parental mean, late puberty with extended growth in boys, optimal nutrition, and favorable polygenic combinations can produce adult height above target. Concern is lower when stature is healthy and velocity is normal. Worry more about crossing percentiles downward or projected height far below target with symptoms (fatigue, delayed puberty, chronic diarrhea) than about exceeding the genetic midpoint.

Should I use adoptive or step-parent heights?

Use biological parents' heights when known, because the formula models genetic transmission. If one biological parent's height is unknown, some clinicians use that parent's sex-matched population median as a placeholder—this calculator requires both entries. Adoptive family stature does not replace genetic data for target-height calculation.

How does this compare to the "double height at age 2" rule?

Doubling a 2-year-old's height is a folk shortcut with inconsistent accuracy across eras and populations. Mid-parental height needs no child measurement and reflects family genetics directly. For medical follow-up, CDC stature-for-age percentiles, growth velocity (cm/year), and—when indicated—bone age outperform both shortcuts.

Is this calculator medical advice?

No. It is educational. Diagnosing pathologic short stature, prescribing growth hormone, or interpreting bone films requires a pediatrician or pediatric endocrinologist. Use official growth charts at well visits and seek care if percentiles cross downward, velocity is low, or projected height diverges from target with unexplained symptoms.

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Pediatrics & growth

Mid-Parental Height Calculator

Estimate your child's genetic adult target height using the clinical Tanner-Davies formula from biological mother and father heights. Shows a ±4 in (±10 cm) teaching range where most children finish. Pair with current-height projection and CDC growth charts at well-child visits—not bone age or growth-hormone prescribing.

Last updated: June 5, 2026

Tanner-Davies target height for boys (+13 cm) and girls (−13 cm)

95% teaching band: ±4 in (±10 cm)

Imperial (ft/in) and metric (cm) parent heights

Genetic benchmark only

Mid-parental height reflects inherited potential, not a guarantee. Nutrition, chronic illness, puberty timing, and endocrine disorders can shift final stature. Use growth-chart percentiles and velocity with your pediatrician.

Target Height Calculator

Estimate a child's final adult height based on parental heights.

Child's Sex

Units

Biological Father's Height

Biological Mother's Height

Estimated Adult Target Height

5' 9.5"

(approx 176.5 cm)

95% Confidence Interval Span

5' 5.5" – 6' 1.5"

*About 95% of children reach final adult height within ±4 in (±10 cm) of this target.

Note: The Tanner-Davies formula estimates genetic potential from parental heights. Nutrition, chronic illness, puberty timing, and endocrine disorders can shift final stature above or below this range.

Example target heights (Tanner-Davies)

Boy — parents 178 & 163 cm (default)

~176.7 cm

166.7–186.7 cm band

Girl — same parents 178 & 163 cm

~164 cm

154–174 cm band

Boy — tall parents 193 & 175 cm

~190.5 cm

180.5–200.5 cm band

Girl — shorter parents 168 & 155 cm

~155 cm

145–165 cm band

Tanner-Davies formula explained

Mid-parental height averages both parents and adjusts for expected adult sex difference before halving.

Metric (centimeters)

Boys: (mother cm + father cm + 13) ÷ 2

Girls: (mother cm + father cm − 13) ÷ 2

Range: target ± 10 cm

Imperial (feet & inches)

Boys: (mother in + father in + 5) ÷ 2

Girls: (mother in + father in − 5) ÷ 2

Range: target ± 4 inches

How pediatricians use mid-parental height

Plot genetic target on growth chart

Pediatricians mark mid-parental height at age 18–20 on stature-for-age charts and compare the child’s percentile curve to that endpoint.

Assess growth adequacy

A child tracking along a percentile that intersects their target height suggests growth is consistent with genetic expectation.

Screen for pathologic short stature

A trajectory finishing well outside the ±4 in band may prompt workup for nutrition, chronic disease, or endocrine disorders.

Counsel parents on expectations

Provides a realistic genetic range—not a guarantee—when discussing family stature and timing of pubertal growth spurts.

Height prediction methods compared

Method	Inputs	Output	Limitation
Mid-parental height (Tanner-Davies) — this tool	Mother and father standing heights	Genetic target + ±4 in (±10 cm) teaching band	Ignores current child height, bone age, puberty stage
Current height ÷ mature fraction	Child sex, age 2–17, standing height cm	Point adult height + ±8 cm band	Needs measured child stature; not purely genetic
CDC/WHO stature-for-age charts	Repeated height vs age	Percentile tracks and growth velocity	Gold standard for pediatrics—not one adult cm number
Bone age × Bayley-Pinneau	Hand/wrist X-ray skeletal 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

Current height percentile trending far below the line that would reach mid-parental target at adulthood
Growth velocity (cm/year) below expected for age and sex on CDC charts
Projected adult height from current stature more than ~10 cm below genetic target with no family explanation
Delayed or absent puberty with short stature past expected timing
Chronic illness, celiac disease, hypothyroidism, Turner syndrome, or growth hormone deficiency concerns on exam

Worked example: default demo (boy)

Mother 163 cm (5 ft 4 in), father 178 cm (5 ft 10 in)

Boy: (mother 5' 4" + father 5' 10" + 5 in) ÷ 2

= (64.0 + 70.0 + 5) ÷ 2 = 69.5 in

95% teaching range: 5' 5.5" – 6' 1.5" (±4 in)

Compare this genetic target with your child's current-height projection on our child height prediction calculator.

Worked example: same parents, daughter

Shows the −13 cm sex adjustment

Girl: (mother 163 cm + father 178 cm − 13 cm) ÷ 2

= (163 + 178 − 13) ÷ 2 = 164 cm

95% teaching range: 154 – 174 cm (±10 cm)

The daughter's target is 13 cm lower than her brother's with identical parents—reflecting average adult female stature, not a prediction of puberty timing.

References

CDC Growth Charts — stature-for-age percentiles
AAP HealthyChildren — understanding growth charts
Tanner JM — Use of parental data in predicting adult height (mid-parental height method)
WHO Child Growth Standards — length/height for age (infants and young children)

Education only. Not for growth hormone prescribing, bone age interpretation, or diagnosing short stature. Use your pediatrician's growth charts, growth velocity, and specialist referral when indicated.

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Pediatrics & growth

Mid-Parental Height Calculator

Last updated: June 5, 2026

Tanner-Davies target height for boys (+13 cm) and girls (−13 cm)

95% teaching band: ±4 in (±10 cm)

Imperial (ft/in) and metric (cm) parent heights

Genetic benchmark only

Target Height Calculator

Estimate a child's final adult height based on parental heights.

Child's Sex

Units

Biological Father's Height

Biological Mother's Height

Estimated Adult Target Height

5' 9.5"

(approx 176.5 cm)

95% Confidence Interval Span

5' 5.5" – 6' 1.5"

*About 95% of children reach final adult height within ±4 in (±10 cm) of this target.

Example target heights (Tanner-Davies)

Boy — parents 178 & 163 cm (default)

~176.7 cm

166.7–186.7 cm band

Girl — same parents 178 & 163 cm

~164 cm

154–174 cm band

Boy — tall parents 193 & 175 cm

~190.5 cm

180.5–200.5 cm band

Girl — shorter parents 168 & 155 cm

~155 cm

145–165 cm band

Tanner-Davies formula explained

Mid-parental height averages both parents and adjusts for expected adult sex difference before halving.

Metric (centimeters)

Boys: (mother cm + father cm + 13) ÷ 2

Girls: (mother cm + father cm − 13) ÷ 2

Range: target ± 10 cm

Imperial (feet & inches)

Boys: (mother in + father in + 5) ÷ 2

Girls: (mother in + father in − 5) ÷ 2

Range: target ± 4 inches

How pediatricians use mid-parental height

Plot genetic target on growth chart

Pediatricians mark mid-parental height at age 18–20 on stature-for-age charts and compare the child’s percentile curve to that endpoint.

Assess growth adequacy

A child tracking along a percentile that intersects their target height suggests growth is consistent with genetic expectation.

Screen for pathologic short stature

A trajectory finishing well outside the ±4 in band may prompt workup for nutrition, chronic disease, or endocrine disorders.

Counsel parents on expectations

Provides a realistic genetic range—not a guarantee—when discussing family stature and timing of pubertal growth spurts.

Height prediction methods compared

Method	Inputs	Output	Limitation
Mid-parental height (Tanner-Davies) — this tool	Mother and father standing heights	Genetic target + ±4 in (±10 cm) teaching band	Ignores current child height, bone age, puberty stage
Current height ÷ mature fraction	Child sex, age 2–17, standing height cm	Point adult height + ±8 cm band	Needs measured child stature; not purely genetic
CDC/WHO stature-for-age charts	Repeated height vs age	Percentile tracks and growth velocity	Gold standard for pediatrics—not one adult cm number
Bone age × Bayley-Pinneau	Hand/wrist X-ray skeletal 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

Current height percentile trending far below the line that would reach mid-parental target at adulthood
Growth velocity (cm/year) below expected for age and sex on CDC charts
Projected adult height from current stature more than ~10 cm below genetic target with no family explanation
Delayed or absent puberty with short stature past expected timing
Chronic illness, celiac disease, hypothyroidism, Turner syndrome, or growth hormone deficiency concerns on exam

Worked example: default demo (boy)

Mother 163 cm (5 ft 4 in), father 178 cm (5 ft 10 in)

Boy: (mother 5' 4" + father 5' 10" + 5 in) ÷ 2

= (64.0 + 70.0 + 5) ÷ 2 = 69.5 in

95% teaching range: 5' 5.5" – 6' 1.5" (±4 in)

Compare this genetic target with your child's current-height projection on our child height prediction calculator.

Worked example: same parents, daughter

Shows the −13 cm sex adjustment

Girl: (mother 163 cm + father 178 cm − 13 cm) ÷ 2

= (163 + 178 − 13) ÷ 2 = 164 cm

95% teaching range: 154 – 174 cm (±10 cm)

The daughter's target is 13 cm lower than her brother's with identical parents—reflecting average adult female stature, not a prediction of puberty timing.

References

CDC Growth Charts — stature-for-age percentiles
AAP HealthyChildren — understanding growth charts
Tanner JM — Use of parental data in predicting adult height (mid-parental height method)
WHO Child Growth Standards — length/height for age (infants and young children)