Child Height Predictor Calculator
Predict your child’s future adult target height based on the clinically validated Mid-Parental Height (Tanner) method.
How to Use the Child Height Predictor Calculator
A child’s future adult stature is one of the most common questions posed to pediatricians. Human height is a polygenic trait: approximately 80% of height variation is determined by inherited genetic variants across hundreds of genomic loci, while the remaining 20% is shaped by childhood nutrition, endocrine health, sleep, and overall wellness.
Formula and Calculation Methodology
- Tanner Mid-Parental Method: The clinical standard equation utilized by pediatric endocrinologists worldwide
- 5-Inch Sex Differential: Represents the average biological sexual dimorphism in adult human height
- Genetic Variance (± 2 inches): Standard deviation accounting for multi-genic polygenic inheritance (covers ~68% of children)
The Mid-Parental Height formula—developed by pediatric researcher Dr. J.M. Tanner—adjusts the biological parents’ heights by 5 inches (the population-level sexual dimorphism difference between adult men and women) to establish a genetic midpoint. Most healthy children reach an adult height within 2 inches (5 cm) of this calculated midpoint.
CDC Pediatric Height Percentile Milestones (50th Percentile Averages)
| Child Age | Boys 50th Percentile | Girls 50th Percentile | Annual Growth Velocity |
|---|---|---|---|
| 2 Years | 34.2 inches (86.8 cm) | 33.7 inches (85.5 cm) | ~3.5 inches / yr |
| 4 Years | 40.3 inches (102.3 cm) | 39.5 inches (100.3 cm) | ~2.5 inches / yr |
| 8 Years | 50.4 inches (128.0 cm) | 50.2 inches (127.5 cm) | ~2.2 inches / yr |
| 12 Years | 58.7 inches (149.1 cm) | 59.4 inches (151.0 cm) | ~3.0 inches (Puberty) |
| 16 Years | 68.3 inches (173.4 cm) | 64.0 inches (162.5 cm) | Growth plates fusing |
Frequently Asked Questions
How accurate is the mid-parental height calculator?
The Tanner Mid-Parental method has an accuracy of approximately ± 2 inches (5 cm) for 68% of children, and ± 4 inches (10 cm) for 95% of children when parents have normal growth trajectories.
What is the ‘Two Times Two’ height rule?
An informal folk guideline states that doubling a boy’s height at age 2 (or a girl’s height at age 18 months) gives a rough estimate of adult height. While occasionally accurate, the Tanner Mid-Parental method is far more scientifically grounded.
When do children stop growing in height?
Girls typically reach their final adult height around age 14 to 16 (approximately 2 years after menarche). Boys experience a later pubertal growth spurt and typically cease vertical growth around age 16 to 18 when long-bone epiphyseal growth plates fuse.