How the child height predictor works
This height calculator combines two proven clinical methods to estimate how tall your child will grow. Both are used by pediatricians and are based on the same growth charts used in clinics worldwide.
1. Percentile-tracking method (current growth curve)
The calculator places your child's current height on the CDC 2000 stature-for-age growth chart for their sex and exact age, giving a height percentile from 1 to 99. It then assumes the child keeps that percentile into adulthood — a 60th-percentile 6-year-old is projected to finish near the 60th-percentile adult height. This method is most reliable for children who are growing steadily along their curve.
2. Mid-parental height method (genetic target)
The mid-parental height (also called the Tanner or target height formula) estimates the child's genetic height potential from both biological parents:
- Boys: (father's height + mother's height + 13 cm) ÷ 2 — e.g. a 175 cm father and 160 cm mother give a target of 174 cm.
- Girls: (father's height + mother's height − 13 cm) ÷ 2 — the same parents give a target of 161 cm.
About two-thirds of children reach adult height within ±8.5 cm of this target. When both parental heights are entered, the calculator blends the genetic target with the percentile projection for the best estimate.
Understanding growth percentiles
Percentiles tell you how your child compares to thousands of other children of the same age and sex in the CDC reference population:
- 50th percentile (median): the average height — half of children are taller, half are shorter.
- 3rd to 97th percentile: the normal range. About 94% of healthy children fall inside this band.
- Below 3rd or above 97th: outside the typical range — worth discussing with a pediatrician, especially if your child also crosses two major percentile lines over time.
Children naturally change percentile in the first years of life, and again around puberty, so a single measurement is only a snapshot — tracking height over time on a growth chart is what matters most.
Average height by age (CDC 2000)
Reference values below are the CDC 50th-percentile median heights with the normal 3rd–97th range, in centimeters.
| Age | Boys — average | Boys — normal range | Girls — average | Girls — normal range |
|---|---|---|---|---|
| 2 years | 86.5 cm | 79.9 – 93.0 | 85.0 cm | 78.4 – 91.5 |
| 3 years | 95.0 cm | 88.0 – 102.6 | 93.9 cm | 86.6 – 101.5 |
| 4 years | 102.2 cm | 94.3 – 110.2 | 100.8 cm | 92.8 – 109.2 |
| 5 years | 108.9 cm | 100.1 – 117.5 | 107.7 cm | 99.1 – 117.0 |
| 6 years | 115.4 cm | 105.9 – 124.8 | 114.7 cm | 105.5 – 124.9 |
| 7 years | 121.8 cm | 111.7 – 132.0 | 121.5 cm | 111.6 – 132.4 |
| 8 years | 127.9 cm | 117.3 – 139.0 | 127.6 cm | 117.1 – 139.1 |
| 9 years | 133.5 cm | 122.2 – 145.4 | 132.9 cm | 121.7 – 145.1 |
| 10 years | 138.6 cm | 126.5 – 151.3 | 138.0 cm | 125.8 – 151.0 |
| 11 years | 143.5 cm | 130.6 – 157.0 | 144.0 cm | 130.5 – 157.8 |
| 12 years | 149.1 cm | 135.4 – 163.4 | 151.2 cm | 137.1 – 164.9 |
| 13 years | 156.1 cm | 141.5 – 171.0 | 157.1 cm | 144.0 – 170.0 |
| 14 years | 163.8 cm | 148.2 – 178.5 | 160.4 cm | 148.0 – 172.8 |
| 15 years | 169.9 cm | 154.4 – 183.9 | 161.9 cm | 149.7 – 174.1 |
| 16 years | 173.5 cm | 158.7 – 187.0 | 162.5 cm | 150.4 – 174.7 |
| 17 years | 175.3 cm | 161.2 – 188.6 | 162.9 cm | 150.7 – 175.1 |
| 18 years | 176.2 cm | 162.5 – 189.4 | 163.1 cm | 150.9 – 175.3 |
| 19 years | 176.6 cm | 163.1 – 189.9 | 163.3 cm | 151.0 – 175.4 |
| 20 years | 176.8 cm | 163.3 – 190.2 | 163.3 cm | 151.1 – 175.5 |
Notice how girls reach nearly their final height around 14 and boys keep growing into late adolescence — reflected in the 20-year adult averages of about 176.8 cm (5 ft 9.5 in) for boys and 163.3 cm (5 ft 4.3 in) for girls.
What determines a child's height?
Growth charts and data sources
This calculator uses the CDC 2000 stature-for-age growth charts — the official LMS parameters for children aged 2 to 20 years, published by the U.S. Centers for Disease Control and Prevention (CDC). The percentile curves shown in the chart above are the CDC's own smoothed values, and monthly values are linearly interpolated exactly as the CDC recommends. You can download the raw reference data from the CDC growth chart data files.