Two parents. One estimate.
Mid-parental height combines the biological parents’ adult heights with a sex-based adjustment to estimate a child’s family target height.
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Height calculator.
Wondering how tall you or your child will be?
Estimate adult height using parents’ heights alone, or add a child’s age, height and weight.
THE CALCULATOR
Estimate adult height
YOUR RESULT
Your estimate appears here.
Enter both parents’ heights to see an adult height estimate and a family target range.
Method: mid-parental height✓ Published methods✓ Clear about uncertainty✓ Private by design
Prediction methods
Methods & sources ↗How both formulas work
Mid-parental height
With parents’ heights in centimeters, add 13 cm for the male formula or subtract 13 cm for the female formula, then divide the total by two. Convert imperial measurements to centimeters first so the same formula is used in either unit system.
Male: (mother + father + 13 cm) ÷ 2
Female: (mother + father − 13 cm) ÷ 2
It offers context about inherited height. It does not require a child’s age, weight or current height. It does not estimate the amount of growth remaining, predict puberty timing or change an adult’s measured height.
Khamis–Roche
Khamis–Roche combines a child’s current height and weight with the unadjusted mean of both biological parents’ heights. Separate coefficients for age and sex give each input a different weight. Adding measurements changes the model; it does not guarantee greater accuracy for every child.
Khamis–Roche: adult height = intercept + stature coefficient × H + weight coefficient × W + parent coefficient × M.
H is current height in inches; W is weight in pounds; M is the unadjusted mean parent height in inches. The equation returns inches, then converts to centimeters.
We use age- and sex-specific coefficients from half-year rows for ages 4–17½. Between rows, we interpolate coefficients linearly (our implementation choice); at table ages we use the exact row. We do not extrapolate.
A statistical point estimate, not a guarantee. No individual prediction interval is provided.
UW MSK Radiology — Adult Stature Predictor · Read the evidence ↗
Think range, not certainty.
Nutrition, health and puberty also affect growth. A family target range is a useful reference, not a promise about one child.
Growth is a bigger picture.
A clinician can look at growth over time, medical history and, when appropriate, bone age. This tool cannot replace that assessment.
What the range means
The Royal Children’s Hospital Melbourne describes a normal final-height range of 8.5 cm on either side of mid-parental height. We label this a family target range. It is not a calculated confidence interval for your child, and the calculator does not assign a probability to the result.
When a simple estimate is insufficient
Changes in growth rate, health conditions, nutrition and treatment can affect eventual height. This formula cannot account for those factors. It also requires both biological parents’ measured adult heights. The two traditional sex adjustments do not model individual hormonal or treatment history.
Inputs of 100–250 cm are a practical data-entry guardrail, not a clinical validation range. If your family’s measurements fall outside it, seek an individual assessment rather than substituting different values.
Formula and ±8.5 cm family target range: Royal Children’s Hospital Melbourne ↗. Guidance reviewed July 2025; checked October 29, 2026. · Read our methodology and evidence notes →
COMPARE THE METHODS
Read the evidence ↗Which question are you asking?
Mid-parental height
How tall will I be based on my parents’ adult heights?
- Inputs
- Both biological parents’ adult heights and the sex used by the formula.
- What to keep in mind
- A family target reference, not an assessment of the child’s current growth. The ±8.5 cm range is not an individual confidence interval.
Khamis–Roche
How tall will my child be using current age, height and weight?
- Inputs
- Age, sex, current height and weight, and both parents’ heights.
- What to keep in mind
- Developed using healthy white American children. Other populations and growth patterns may have different errors. No personal prediction interval is provided.
Growth tracking
How is a child’s measured growth changing over time?
- Inputs
- Repeated measurements with dates, interpreted using an appropriate age- and sex-specific growth chart.
- What to keep in mind
- Percentiles describe a reference population. They do not guarantee a future adult height or diagnose a growth condition on their own.
Choose the model based on the measurements you have. The family target range belongs only to the parents-only method; it is not a Khamis–Roche error range.
How the Khamis–Roche height predictor works
Khamis–Roche combines a child’s current height and weight with the unadjusted mean of both biological parents’ heights. Separate coefficients for age and sex give each input a different weight. Adding measurements changes the model; it does not guarantee greater accuracy for every child.
Khamis–Roche: adult height = intercept + stature coefficient × H + weight coefficient × W + parent coefficient × M. H is current height in inches; W is weight in pounds; M is the unadjusted mean parent height in inches. The equation returns inches, then converts to centimeters.
Which ages can use the child + parents method?
This calculator accepts 4 years 0 months through 17 years 6 months. For younger children, the parents-only method can provide family-height context. Outside the supported ages, we show an error rather than extrapolating or switching formulas automatically.
How to interpret a child-height prediction
The original model was developed using 223 white American boys and 210 white American girls in the Fels Longitudinal Study. It does not measure bone age or the timing of puberty. Results may differ for children with other backgrounds or conditions affecting growth. We show a point estimate without a personal prediction interval.
A Khamis–Roche worked example
For a 12-year-old boy who is 150 cm tall and weighs 40 kg, with a mother of 160 cm and a father of 180 cm, the adult-height estimate is 177.8 cm. The parents-only method gives 176.5 cm for the same family. These are separate model outputs, not endpoints of a range.
UW MSK Radiology — Adult Stature Predictor · Khamis & Roche (1994), Pediatrics 94:504–507
Two worked examples
Let’s put numbers to it.
With a mother of 165 cm and a father of 180 cm, the male formula gives 179 cm, with a reference range of 170.5–187.5 cm. The female formula gives 166 cm, with a reference range of 157.5–174.5 cm.
(165 + 180 + 13) ÷ 2179 cmFamily target range: 170.5–187.5 cm
(165 + 180 − 13) ÷ 2166 cmFamily target range: 157.5–174.5 cm
GOOD QUESTIONS
A little more clarity.
What a height predictor can—and can’t—tell you.
How tall will my child be?
To estimate how tall your child will be, select Child + parents if they are between 4 and 17½ years old. The Khamis–Roche method combines their current age, height, and weight with both biological parents’ heights. If your child is under 4 or current measurements are unavailable, the Parents only (mid-parental) option provides a family target reference range.
How tall will I be as an adult?
If you only know your biological parents’ heights, use the Parents only (mid-parental) calculation. It determines your sex-adjusted mid-parental height and a ±8.5 cm family target reference range based on Royal Children’s Hospital Melbourne guidance. If you are aged 4–17½ and have current growth measurements, Child + parents offers an estimate based on current growth data.
What is the Tanner formula for height prediction?
The Tanner formula (also called the Tanner mid-parental target height method) was developed by pediatrician J.M. Tanner in 1970. It estimates a child’s adult target height from biological parents’ statures: adding 13 cm (5 in) for boys or subtracting 13 cm for girls, then dividing by two. Royal Children’s Hospital Melbourne guidance pairs this with a ±8.5 cm family target reference range.
How accurate is this adult height calculator?
Neither method guarantees a child’s final height. The parents-only estimate includes the RCH ±8.5 cm family target reference range. Khamis–Roche gives a point estimate; its errors depend on age, measurement quality and how well the child matches the study population.
Does it use my child’s current height or age?
Choose Child + parents to use age, current height and weight with Khamis–Roche, for ages 4–17½. Parents’ heights only uses the mid-parental formula and does not use the child’s current measurements. Neither method assesses bone age or puberty timing.
Can I use it if a parent’s height is unknown?
The method requires both biological parents’ heights. Substituting another relative’s height has not been validated for this formula.
Can this tell me if growth is on track?
No. If you have concerns, ask a clinician to review measured growth over time and the child’s health and puberty history. A single estimate cannot diagnose a growth condition.