Child Growth LabMid-Parental Height Calculator
- Uses the measured adult heights of both biological parents.
- Calculates a central family-height estimate and approximate range.
- Supports cm and decomposed ft/in inputs.
- Uses one canonical 13 cm formula in both unit systems.
- This is not a precise adult-height prediction or diagnosis.
Pediatric growth calculators based on CDC and WHO growth standards.
How to use the mid-parental height calculator
Select the historical boy/male or girl/female formula, choose cm or ft/in, and enter the measured adult heights of both biological parents after growth is complete. Prefer reliable measurements without shoes rather than height in shoes, an identity-document estimate, or a guessed value.
The calculator accepts 50–274.32 cm after canonical conversion only as a technical guard against obvious unit or entry errors. It is not a normal adult-height range and does not diagnose short stature, tall stature, skeletal disease, or genetic disease.
What the family-height estimate means
The center and surrounding range describe family-height background. They do not state how tall a child should become, diagnose short or tall stature, or guarantee an adult height.
Need a fuller explanation of the estimate? Read What Is Mid-Parental Height?
How the boy and girl formulas differ
The boy/male formula is (father height + mother height + 13 cm) / 2. The girl/female formula is (father height + mother height − 13 cm) / 2. Equivalently, the parental average is adjusted by +6.5 cm or −6.5 cm.
Why the range is approximate
This page uses the AAP convention of center ±4 in. Four inches converts exactly to 10.16 cm and is displayed to parents as about 10.2 cm. The range is not a guarantee or individualized prediction interval, and other resources may use different conventions.
Why Metric and US units must give the same result
US heights are converted using exactly 1 in = 2.54 cm before the canonical 13 cm formula is applied. Some US references describe a 5-inch adjustment before averaging, but 5 in and 13 cm are not identical. This site uses 13 cm for both unit modes so unit choice cannot change the canonical result.
What this calculator does not include
The formula does not include the child's current height, age, growth velocity, puberty timing, bone age, health, nutrition, or other genetic factors. It is not Khamis–Roche, a bone-age prediction, a diagnosis, or a treatment tool.
A parent's current measured height may be below younger peak adult height because of age, spinal compression, or other height loss. This calculator does not correct for parental age, reconstruct an earlier peak height, or ask the user to add an arbitrary amount. If reliable clinical records from different times disagree, an appropriate professional should decide which record to use.
Mid-parental height versus current height percentile
Mid-parental height uses only the two biological parents' adult heights. The Height Percentile Calculator instead compares a child's current standing height with a CDC age- and sex-specific reference.
Why growth velocity and the growth curve matter
The Growth Velocity Calculator compares height measurements from two dates. The Child Growth Chart Calculator helps review current measurements and reference positions. Serial measurements provide more information than this family-height estimate alone.
A child whose current height or growth trend differs from the family-height estimate is not diagnosed by this calculator. Review accurate serial measurements with a healthcare professional when there are concerns.
Parents with very different or extreme heights
The simple formula can have more regression bias when parents are very tall, very short, or differ greatly in height. The broad positive input policy is now a 50–274.32 cm technical entry rule after unit conversion, not a statement about normal adult height. Values outside it should prompt a check of units and the measured adult-height record, not a diagnosis.
Alternative clinical methods
RCPCH digital growth charts use parental height z-scores and a regression factor. That is a separate method and is not mixed into this calculator. Current-height prediction, bone-age methods, and Khamis–Roche are also outside this page.
The retained 2024 research source evaluates additional age-, sex-, and regression-related modeling. This calculator does not implement that experimental model or present it as the current AAP method.
Worked examples
With a biological father at 180 cm and biological mother at 165 cm, the parental average is 172.5 cm. The boy/male adjustment is +6.5 cm, giving a center of 179.0 cm and an approximate range of 168.8–189.2 cm.
For the same parent heights, the girl/female adjustment is −6.5 cm, giving a center of 166.0 cm and an approximate range of 155.8–176.2 cm.
As a display-rounding check, a father at 180 cm and mother at 172.6 cm produce a boy/male center of 182.8 cm, displayed as 6 ft 0.0 in rather than 5 ft 12.0 in.
Sources and common questions
This page uses the canonical 13 cm center formula and the AAP ±4 in range convention. Different resources may use other ranges or regression methods; the RCPCH z-score regression method is not implemented here.
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Helpful context
Frequently asked questions
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 sex adjustment. It is not a diagnosis or a promise of one child’s adult height.
How is mid-parental height calculated?
This page averages both biological-parent heights, then adds 6.5 cm for the boy/male formula or subtracts 6.5 cm for the girl/female formula. This is algebraically equivalent to adding or subtracting 13 cm before dividing the total by two.
What does the approximate target-height range mean?
The page applies the AAP ±4 in convention, exactly ±10.16 cm, around the center. It is an approximate family-height range, not an individualized confidence interval or guarantee.
Is this a precise prediction of adult height?
No. Current height, growth velocity, puberty timing, bone age, health, nutrition, and many genetic factors are not inputs. A child may grow inside or outside the displayed range.
Why are both biological parents’ heights needed?
The published formula is defined from the adult heights of both biological parents. If either height is unavailable, this calculator cannot produce the formula as specified.
Why does the formula ask for the child’s sex?
The historical formula provides separate boy/male and girl/female calculations using a +6.5 cm or −6.5 cm adjustment from the parental average. Choose the formula used in the child’s medical record.
Will cm and ft/in give the same result?
Yes. US inputs are converted exactly using 1 inch = 2.54 cm, and both unit modes then use the same canonical 13 cm formula. The selected unit only changes how the result is displayed.
What if the parents are very tall, very short, or very different in height?
Use reliable shoe-free adult measurements taken after growth was complete. A current measurement can be lower than younger peak adult height because of age, spinal compression, or other height loss. This calculator does not correct for parental age, reconstruct peak height, or apply regression, so do not add an arbitrary number of centimeters. If reliable clinical records differ, an appropriate professional should decide which record to use. The separate RCPCH z-score method and the 2024 experimental regression model are not implemented here.
Does the calculator use the child’s current height or age?
No. It uses only the two biological parents’ measured adult heights and the selected historical sex formula. It does not use the child’s current height, age, bone age, or puberty stage.
What is the difference between mid-parental height and a height percentile?
Mid-parental height describes family-height background. A height percentile compares the child’s current measured height with a reference for the child’s age and sex. They answer different questions.
When should growth be discussed with a healthcare professional?
Discuss concerns about current height, a slowing growth rate, changes across the growth curve, puberty timing, or health with a qualified healthcare professional. Accurate serial measurements are more informative than this estimate alone.
Does this site save the heights?
Calculator inputs are processed in your browser and are not saved as a child health record or sent to an external calculation service.