Height predictor: how tall will I be?

A height predictor estimates adult height from what is known today. The quickest version uses your parents: average their heights, then add 6.5 cm (2.5 in) for a boy or subtract it for a girl, give or take about 8.5 cm. Add your own age, height and weight and this Height Predictor Calculator also runs the Khamis-Roche method, whose authors reported 90% of predictions within about 5 cm (2 in). It is an estimate, not medical advice.

For yourself or your child Ages 4–17.5 Free · no sign-up · runs in your browser

Enter your details

Predicting for yourself? Enter your own numbers. For a son or daughter, enter theirs.

Units

Height

Weight

Sex Age (years)

Khamis-Roche covers ages 4–17.5. Outside that range you still get the parents-only estimate.

Current height (cm) Current weight (kg)

Father’s height (cm)

Mother’s height (cm)

All math runs in your browser. Nothing you enter is uploaded or stored.

Predicted adult height

Fill in the details and press Predict adult height. You get a Khamis-Roche prediction (when age, height and weight are filled in) plus the mid-parental target range.

Educational estimate only. This is not medical advice and cannot diagnose a growth problem. Adult height depends on genetics, nutrition, health and the timing of puberty. For any concern about growth, see a pediatrician or family doctor.

How this height predictor works

The calculator runs two published methods side by side and shows both, because they answer slightly different questions. Neither can see the future, so each result comes with a range.

Method 1: Khamis-Roche (uses your own measurements)

The Khamis-Roche method predicts adult height from four inputs: current age, height and weight, plus the average of the two parents’ heights. It was published by Khamis and Roche in Pediatrics in 1994 as a way to predict adult stature without a hand X-ray. Each age and sex has its own published coefficients. The authors reported that 90% of predictions fell within about ±5.3 cm (2.1 in) for boys and ±4.3 cm (1.7 in) for girls. It covers ages 4 to 17.5 and was developed in healthy US children. More detail on the Khamis-Roche calculator page.

Method 2: mid-parental height (parents only)

The mid-parental or target-height formula uses only the parents: (father + mother) ÷ 2, plus 6.5 cm for a boy or minus 6.5 cm for a girl. The usual target range is about ±8.5 cm around that figure, which is wide because the formula knows nothing about how you are actually growing. See the mid-parental height calculator for the worked steps.

Why you get a range, not one number

Final adult height is shaped by genetics, nutrition, general health, sleep and above all the timing of puberty. Someone who matures early or late can finish outside even a good estimate. No calculator is 100% accurate; our comparison of the most accurate height prediction methods lists what each one can and cannot do. If you are a teenager wondering how much growing is left, the Am I done growing? tool answers that more directly. If you would rather answer one question at a time and skip what you don’t know, the how tall will I be quiz picks the formula for you.

Common questions

How tall will I be if I only know my parents’ heights?: Leave age, height and weight blank. The tool then gives the mid-parental target height and its range of about ±8.5 cm.
How accurate is a height predictor?: For Khamis-Roche, the original paper reported 90% of predictions within roughly 4–5 cm (about 2 in) of adult height in the children studied. One in ten fell outside that, and the study group was healthy white US children, so treat your result as a reasonable ballpark.
Does it work for boys and girls?: Yes. Both methods use different numbers for each sex; pick the sex first and the right coefficients are used.
Can I use it for a baby or toddler?: Under age 4 only the parents-only estimate applies. The baby height predictor explains what is and is not predictable that early.
Where does my height rank today?: The height percentile calculator places a height on the CDC growth chart for ages 2 to 20.
Is anything I type uploaded?: No. The calculation happens in your browser. See Privacy.

Sources: Khamis HJ, Roche AF. “Predicting adult stature without using skeletal age: the Khamis-Roche method.” Pediatrics. 1994;94(4):504–507; erratum 1995;95(3):457. Tanner JM, Goldstein H, Whitehouse RH. “Standards for children’s height at ages 2–9 years allowing for height of parents.” Archives of Disease in Childhood. 1970;45:755–762. Full list on the About page.