Child Height Predictor
Predict your child's adult height using the Mid-Parental Height, Khamis-Roche, and Multiplier methods
No child measurements? Enter only parental heights for a Mid-Parental Height estimate.
Child's current standing height
Required for Khamis-Roche method (age 4–17.5)
Enter Details to Predict Height
Enter parental heights (and optionally your child's age, height, and weight) to predict your child's adult height.
How to Use the Child Height Predictor
Select Units and Enter Parental Heights
Choose metric (cm/kg) or imperial (ft/in/lbs) units, then enter the biological father's and mother's heights. These two values alone are enough to generate a Mid-Parental Height prediction — useful for expectant parents or when child measurements are unavailable. Make sure to use the parents' actual standing heights, not estimates or rounded numbers, for the most accurate prediction.
Enter Your Child's Details
For a more accurate Khamis-Roche prediction, enter the child's sex, current age (years and months), current standing height, and current weight. You can either enter the age directly or use the date of birth picker to calculate it automatically. The child's age must be between 4.0 and 17.5 years for the Khamis-Roche method to apply. Height and weight should be measured recently for the best accuracy.
Review the Three-Method Comparison
The results panel shows predictions from up to three methods simultaneously: Mid-Parental Height, Khamis-Roche (if age 4–17.5 and weight is provided), and the Multiplier method (if age and height are provided). The primary recommended prediction is highlighted at the top. Each method shows its confidence range and typical accuracy. Compare all three to understand the range of plausible adult heights.
Interpret the Charts and Growth Stage Notes
The height comparison bar chart shows the child's current height, predicted adult height, and both parents' heights side by side so you can visualize where the prediction falls relative to the family. The remaining growth bar shows how much more height to expect. The percentile donut shows where the predicted height ranks in the adult population. The growth stage note explains typical growth rates for your child's current age bracket.
Frequently Asked Questions
How accurate are child height predictions?
The accuracy depends on which method is used. The Khamis-Roche method — the most accurate non-clinical approach — is typically within 5.3 centimeters (about 2 inches) for 90 percent of children when the child is between 4 and 17.5 years old. The simpler Mid-Parental Height method has a wider margin of approximately plus or minus 8.5 centimeters (3.5 inches). No formula accounts for individual variation in the timing of puberty, nutritional adequacy, illness, or other environmental factors. Think of the prediction as the center of a range, not a definitive final height. If your child's actual growth is significantly above or below predictions over multiple years, a pediatric endocrinologist can assess whether an underlying growth disorder is present.
At what age can you predict a child's height most accurately?
Prediction accuracy generally improves as the child gets older, because older children have already completed more of their growth trajectory and there is less remaining uncertainty. The Khamis-Roche method is validated for ages 4.0 to 17.5 years and becomes increasingly precise in the pre-pubertal and early pubertal years (ages 8-12 for girls, 9-13 for boys). Predicting height in infancy or early toddlerhood is much less reliable because early growth is heavily influenced by nutrition and catch-up or catch-down growth. By age 8, Khamis-Roche predictions are typically within a narrower range than earlier predictions.
Why do the three methods give different predictions?
Each method uses different inputs and mathematical approaches, so some variation is expected. The Mid-Parental Height method relies solely on genetics (parental heights) and uses a simple adjustment formula. It does not account for whether the child is currently growing fast or slow relative to peers. The Khamis-Roche method incorporates the child's current height, weight, and parental heights into a regression equation, so it captures the child's actual growth trajectory. The Multiplier method uses only the child's current height and age, assuming that height at any age is a fixed proportion of adult height based on population averages. When the three predictions are close together, you can have more confidence in the range. When they differ substantially, it may indicate that the child's growth is atypical in some way — worth discussing with a pediatrician.
Can I use this calculator if I don't know the father's or mother's height?
Yes. If parental heights are unknown, you can use the Multiplier method alone by entering only the child's current height and age. This method does not require any parental height information. You can also use an estimated average adult height for the unknown parent — the average adult male height is approximately 176 cm (5'9") and the average adult female height is approximately 163 cm (5'4") in the United States. For adopted children or situations where biological parental heights are unavailable, the Multiplier method provides a reasonable estimate based purely on the child's current growth trajectory. Note that Mid-Parental Height and Khamis-Roche predictions require both parental heights and will not calculate without them.
What should I do if my child's growth seems off-track?
A single height measurement compared to a prediction tool is not sufficient to diagnose a growth problem. What matters is the child's growth velocity over time — how much they are growing per year compared to expected rates for their age. Red flags that warrant a pediatric consultation include: growing less than 5 cm per year before puberty, significant crossing of height percentile lines on a growth chart (dropping from the 75th to the 25th percentile over 2 years, for example), signs of very early or very late puberty, height that is significantly below both parents' genetic potential, or associated symptoms like unexplained weight loss, fatigue, or hormonal changes. Your child's pediatrician tracks growth at every well-child visit and can refer to a pediatric endocrinologist if a growth disorder is suspected.
What is bone age and when is it used?
Bone age is a measure of skeletal maturation determined by X-raying the left hand and wrist and comparing the appearance of growth plates (epiphyseal plates) to a standard reference atlas. A child's bone age can be ahead of (advanced), behind (delayed), or equal to their chronological age. Bone age is used clinically when a child's height prediction is uncertain due to early or late puberty — a child with a very advanced bone age may have less remaining growth potential than their chronological age would suggest, while a child with a delayed bone age may have more. Clinical methods like Bayley-Pinneau and Greulich-Pyle combine bone age with current height to refine predictions significantly. These methods require radiological assessment and interpretation by a qualified healthcare provider and cannot be replicated in an online calculator.