Predicted Adult Height Calculator
Predicted Adult Height Calculator
Predicting a child’s adult height is a common question at pediatric visits. While no method is perfectly accurate, several well-established formulas provide reasonable estimates based on the child’s current growth and their parents’ heights. The most commonly used methods are the Mid-Parental Height formula (also called the Tanner method) and the growth-factor projection based on bone age. This calculator uses the Mid-Parental Height method, which is the standard approach recommended by pediatric endocrinologists.
The Mid-Parental Height Formula
The Mid-Parental Height (MPH) formula calculates a child’s expected adult height based on the heights of both biological parents:
- Boys: (Father’s height + Mother’s height + 13 cm) / 2
- Girls: (Father’s height + Mother’s height – 13 cm) / 2
The result gives the target height with a standard deviation of approximately ±5–7 cm. This means that 95% of children will fall within ±10–14 cm of the predicted height. The 13 cm adjustment accounts for the average sex difference in adult height. This formula was developed by James Tanner, a pioneer in childhood growth research, and remains the most widely used prediction method in clinical practice.
Limitations
The Mid-Parental Height formula assumes that the child has no underlying growth disorders and that both parents are of average height (not extremely tall or short). It does not account for genetic conditions, chronic illness, nutritional status, or bone age. For a more precise prediction, a pediatrician may order a bone age X-ray of the left hand and wrist, which can be combined with height prediction tables for a more accurate estimate.
Predicted Adult Height Calculator
Predicted Adult Height Calculator
Frequently Asked Questions
How does the mid-parental height formula work?
For boys: (father’s height + mother’s height + 13 cm) / 2. For girls: (father’s height + mother’s height – 13 cm) / 2. The 13 cm accounts for the average sex difference in adult height. The result is the expected adult height (target height).
How accurate is predicted adult height?
Mid-parental height predicts within about ±8.5 cm (95% confidence interval) of final adult height for most children. It is a genetic estimate and does not account for nutrition, chronic illness, or endocrine conditions.
When is height prediction most accurate?
Prediction is more reliable when the child is healthy and growing along a normal curve. Bone-age-based methods (e.g., Bayley-Pinneau) are more accurate during puberty but require a hand X-ray interpreted by a specialist.
What if my child’s height differs a lot from the prediction?
A difference of more than 8-10 cm from the predicted range, or growth that crosses percentile lines, warrants evaluation by a pediatrician or pediatric endocrinologist to rule out growth disorders.
Authoritative Resources
Written by Dr. Sarah Williams, MD (Pediatrics) | Medically approved by Dr. Ahmed Raza, MD (Pediatrics) | Updated for 2026
Disclaimer: This calculator is for general informational purposes only and is not a substitute for professional medical advice. Always consult your pediatrician.
