What Is Mid-Parental Height?

Mid-parental height is a rough family-height reference calculated from the measured adult heights of both biological parents and a historical boy/male or girl/female adjustment.

The result includes a central family-height estimate and an approximate range around that center.

It is not the child’s current height, current height percentile, growth velocity, bone age, or a precise forecast of adult height.

A child may eventually grow inside or outside the displayed range. The result does not diagnose short or tall stature, identify the cause of a growth pattern, or determine whether treatment is needed.

Height is strongly influenced by inherited factors, so the measured adult heights of biological parents can provide useful family context when a child’s growth is assessed.

The mid-parental formula compresses that family information into one central estimate. The surrounding range provides a broad comparison area rather than an individualized prediction.

The center does not describe how tall the child should be at the current age and does not mean the child must reach that exact adult height.

A child’s current measurement, percentile trajectory, growth rate, maturation, health, and clinical findings remain separate information.

The estimate is most useful as one part of a broader growth assessment, not as a stand-alone conclusion.

The current calculation is a historical sex-adjusted mid-parental-height method. Tanner, Goldstein, and Whitehouse published the original work in 1970 using children ages 2–9 and a British reference context.

That history does not make the method useless: AAP materials still present it as a rough target-height calculation, and Pediatric Endocrine Society resources use family height as one part of growth assessment. The formula is also simple enough to reproduce and inspect clearly.

The historical method is not precisely recalibrated for every modern population, a certain adult height for one child, or the most precise model for every clinical purpose. Citing AAP, PES, or the original authors does not imply that they endorse Child Growth Lab.

This site uses the following canonical metric formula:

Boy/male center = (father height + mother height + 13 cm) ÷ 2

The same calculation can be written as:

Boy/male center = parental average + 6.5 cm

For a biological father measuring 180 cm and a biological mother measuring 165 cm, the parental average is 172.5 cm. Adding 6.5 cm gives a central estimate of 179.0 cm.

The formula uses measured adult heights. It does not use the child’s current age, height, growth curve, puberty stage, or bone age.

Choose the boy/male formula only when that is the historical formula used in the child’s medical record or clinical context. The calculator does not determine which formula is appropriate.

This site uses the following canonical metric formula:

Girl/female center = (father height + mother height − 13 cm) ÷ 2

The same calculation can be written as:

Girl/female center = parental average − 6.5 cm

For a biological father measuring 180 cm and a biological mother measuring 165 cm, the parental average is 172.5 cm. Subtracting 6.5 cm gives a central estimate of 166.0 cm.

The formula uses the same two parental-height inputs as the boy/male formula. Only the historical sex adjustment changes.

The calculator does not assess chromosomes, hormones, puberty, gender identity, skeletal maturity, or a medical condition. It only applies the selected historical formula.

The published formula is defined from the measured adult heights of both biological parents.

Use adult height measurements without shoes when available. A remembered or self-reported height may contain rounding or recall error, so a recent careful measurement is preferable.

If either biological-parent height is unavailable, this calculator cannot reproduce the formula as defined. Do not invent, substitute, or estimate a missing value solely to obtain a result.

Heights of adoptive parents, guardians, step-parents, or other relatives do not replace the two biological-parent variables in this particular formula.

That limitation describes the mathematical inputs of the published method. It is not a statement about parenthood, caregiving, or the legitimacy of any family relationship.

Use reliable adult heights measured after growth is complete, without shoes. An accurate measurement or dependable clinical record is preferable to a recalled, self-reported, identification-document, or rounded height.

A parent’s current measured height can be below their younger peak adult height because of age, spinal compression, or other height loss. This site does not correct for parental age, reconstruct peak adult height, or tell users to add an arbitrary number of centimeters. If reliable records conflict, an appropriate healthcare professional should decide which measurement fits the assessment.

If either biological parent’s height is unavailable, do not invent it or replace it with a population average. The inability to run this formula is an input limitation, not a judgment about adoptive parents, guardians, step-parents, or other caregiving relationships.

Each parent’s canonical height accepts 50–274.32 cm, inclusive. That wide interval is only a technical guard against likely unit or entry errors. It is not a normal adult-height range or a diagnostic boundary for short stature, very tall stature, skeletal disease, or genetic disease.

The traditional mid-parental method uses separate boy/male and girl/female formulas to account for average differences in adult height between the two historical reference groups.

Boy/male and girl/female are names for the two branches of this historical binary sex-adjusted formula. The calculation does not inspect chromosomes, gonadal or hormonal status, puberty, skeletal maturity, gender identity, differences of sex development, or gender-affirming treatment.

The site cannot decide which branch fits a complex clinical situation. Follow the child’s medical record, the applicable clinical protocol, and an appropriate professional; selecting a formula is not a judgment about identity.

The selected formula changes the parental average by +6.5 cm or −6.5 cm. It does not individualize the adjustment for puberty timing, hormones, skeletal maturity, or another biological characteristic.

Some references express the pre-division adjustment as 5 inches in US units and 13 cm in Metric units. Five inches equals 12.7 cm, so the two expressions are not exactly identical.

This site converts all US height inputs using exactly 1 inch = 2.54 cm and then applies the canonical 13 cm formula. It does not run a separate 5-inch formula.

Using one canonical formula prevents the selected display unit from changing the underlying result.

This site displays a range centered on the calculated mid-parental height.

Lower bound = center − 10.16 cm

Upper bound = center + 10.16 cm

The half-width of 10.16 cm is exactly 4 inches. It follows the AAP convention of showing mid-parental height plus or minus 4 inches.

AAP eQIPP describes this target-height range as approximately 2 standard deviations and states that about 95% of children are within 4 inches of the calculated center. That is a population convention, not a 95% probability calculated for the child using this site.

This site uses the exact conversion 4 in × 2.54 = 10.16 cm. AAP materials may round the metric half-width to 10.2 cm or 10 cm; retaining 10.16 cm keeps the two unit modes equivalent.

The result is labeled an approximate family-height range because the simple calculation does not use child-specific measurements, maturation, bone age, health, or a statistical model fitted to the individual child.

The displayed range is not an individualized confidence interval, guarantee, diagnosis, or boundary that a child must remain within.

Other clinical systems may use different ranges, centiles, z-scores, or regression methods. Their outputs should not be mixed with this range as though they were the same model.

Mid-parental height uses only the measured adult heights of both biological parents and the selected historical formula.

A current height percentile compares the child’s measured standing height with children of the same age and sex in a defined reference.

The two results answer different questions. A child’s current percentile can be above, below, or near the family-height estimate without either result automatically being wrong.

Use the Height Percentile Calculator for the current CDC reference position and read What Does a Child’s Height Percentile Mean? for interpretation.

Neither one current percentile nor one mid-parental estimate can replace a series of accurate height measurements.

The term target height is sometimes used for mid-parental height, but the simple result should not be read as an exact destination.

This calculator does not use the child’s current height, age, earlier measurements, growth velocity, puberty timing, skeletal maturity, bone age, health conditions, medications, or nutrition.

It therefore cannot state that the child will become a particular number of centimeters or inches tall.

This page does not implement the two-years-times-two method, Khamis–Roche prediction, bone-age prediction, current-centile projection, or another adult-height model.

Even a clinical prediction that uses more information remains an estimate rather than a guarantee.

Adult height is influenced by many genetic variants rather than one single height gene.

Growth can also be affected by maturation, hormones, nutrition, medications, chronic illness, genetic conditions, skeletal conditions, and other health or environmental factors.

The mid-parental calculation does not measure any of those influences and cannot determine why a child is shorter or taller than the family estimate.

A difference from the center or range is not proof of disease, inadequate nutrition, parenting, or a problem with either parent’s height.

Do not use the estimate to start supplements, restrictive diets, hormone treatment, exercise programs, or other attempts to alter height.

Growth velocity describes how quickly height changed between two dated measurements. Mid-parental height contains no measurement dates and does not calculate a rate.

Puberty timing can also affect the current growth pattern. Children with similar family-height backgrounds may enter the pubertal growth spurt at different ages.

A child may temporarily be shorter or taller than peers because of maturation timing without the mid-parental formula being able to explain the pattern.

Read What Is Growth Velocity in Children? for an explanation of growth rates and use the Child Growth Velocity Calculator when two dated measurements are available.

A slowing or persistently unexpected growth pattern deserves clinical context, but one calculated rate or family-height estimate does not establish a diagnosis.

Bone age is an assessment of skeletal maturity, commonly based on an X-ray of the hand and wrist in an appropriate clinical setting.

A clinician may combine bone age with current height, age, growth history, puberty information, and other findings when evaluating growth or estimating remaining growth.

The Mid-Parental Height Calculator does not request, calculate, interpret, or predict bone age.

It also does not convert the family-height estimate into a bone-age-based adult-height prediction.

Do not obtain imaging, testing, or treatment solely because an online family-height estimate differs from a current measurement. Those decisions require an appropriate healthcare professional.

The simple arithmetic formula may be less representative when one or both parents are very tall or very short, or when the two parental heights differ substantially.

Regression toward the population mean means that children of parents at height extremes are, on average, often less extreme than a direct family average might suggest. It does not mean one particular child must move toward the population average.

Wright and Cheetham found that simple parental-height methods can mislead when parents are unusually tall or short, even though they can provide useful context around average parental heights.

RCPCH digital growth charts use a separate method based on parental height z-scores and a regression factor. That method is not the same as the simple 13 cm formula.

This site does not calculate the RCPCH mid-parental centile, parental z-scores, regression factor, or centile-space comparison. RCPCH’s three-centile-space assessment clue cannot be converted into this site’s ±10.16 cm range, a number of centimeters below the center, automatic referral, or a diagnosis.

The calculator’s broad positive input maximum is a technical protection against likely entry or unit errors. It is not a statement that every accepted value is biologically typical.

A 2024 study by Zeevi and colleagues evaluated the traditional method in 23 large nuclear families, with about 11 adult children per family on average. In that specific cohort, the standard method explained about 36% of adult-height variation and underestimated height by about 2.7 cm on average.

The researchers proposed adjustments for parental age, a different sex correction, and regression toward the mean. Those findings and figures describe that study cohort; they are not this site’s accuracy for an individual child and do not establish universal performance.

The proposed research model is not the current AAP simple formula and is not implemented here. Users should not add 2.7 cm or make another manual change to this site’s result to imitate it.

Use the Mid-Parental Height Calculator to calculate the simple family-height center and approximate range from both biological parents’ measured adult heights.

Read What Is Mid-Parental Height? when the question is what the estimate and range mean and what the method does not include.

Use the Height Percentile Calculator to compare the child’s current standing height with the CDC age- and sex-specific reference.

Read What Does a Child’s Height Percentile Mean? for an explanation of current percentile position, repeated measurements, and interpretation boundaries.

Use the Child Growth Velocity Calculator to calculate recorded height change between two dates.

Read What Is Growth Velocity in Children? to understand why a growth rate is different from a percentile or family-height estimate.

Read How to Read a CDC Growth Chart for chart axes, percentile curves, plotting, and repeated-measurement context.

Use the Child Growth Chart Calculator to review current CDC height and weight reference positions. It does not predict adult height.

A calculator cannot decide whether a child’s height, growth rate, puberty pattern, or family-height difference requires medical evaluation. Consider discussing growth with a healthcare professional when:

Pediatric Endocrine Society guidance treats height substantially below genetic potential as one evaluation clue. Applying that clue requires an accurate current height, an age- and sex-specific reference, serial growth, growth velocity, puberty context, family history, measurement quality, and clinical findings.

This site’s simple center and range cannot determine whether a child is significantly below genetic potential, has short or tall stature, or needs referral, tests, or treatment.

• accurate serial height measurements show decreasing growth velocity or downward crossing of height percentiles after early childhood;
• the child’s current height is well below the age- and sex-specific reference or substantially different from the expected family-height context;
• puberty appears unusually early, delayed, stalled, or different from the child’s broader growth pattern;
• abnormal body proportions, chronic illness, significant symptoms, medication exposure, nutritional concerns, or a known genetic or skeletal condition are present;
• you are uncertain about parental-height measurements, the selected historical formula, bone age, adult-height prediction, or whether a specialist assessment is appropriate.

Bring accurate dated height measurements, the growth chart, both biological parents’ measured adult heights when available, earlier medical records, puberty history, medication history, and any prior bone-age or laboratory reports.

Do not use one mid-parental height result alone to diagnose short or tall stature, order testing, request imaging, start supplements or hormones, change treatment, or decide that professional follow-up is unnecessary. Read the Medical Disclaimer.