Educational tool — not medical advice. Height predictions are estimates with significant uncertainty. Verify with a qualified healthcare professional.
How This Height Predictor Works
This calculator uses two independent methods to estimate your child's adult height. Using both methods together gives you a more complete picture than either one alone.
Method 1: Growth Curve Projection
This method analyzes where your child currently falls on the CDC growth chart and projects what height they would reach as an adult if they continue tracking along the same percentile curve. A child currently at the 75th percentile for height at age 5 would be projected to reach the 75th percentile of adult height — about 178 cm (5'10") for boys or 166 cm (5'5") for girls.
This is a trajectory-based prediction that captures your child's actual growth so far. Its main limitation is that children can shift percentiles during puberty, especially if they enter puberty earlier or later than average.
Method 2: Mid-Parental Target Height
This classic method — also called the Tanner method — estimates your child's genetic height potential from both parents' heights. The formula adjusts for the average 13 cm (5 inch) height difference between adult men and women:
- Boys: (Mother's height + Father's height + 13 cm) ÷ 2
- Girls: (Mother's height + Father's height − 13 cm) ÷ 2
The result has a standard error of approximately ±8.5 cm (3.3 inches), meaning 68% of children end up within that range of the prediction. This method captures genetics but doesn't account for the child's own growth trajectory.
Why Two Methods?
When both methods agree closely, you can have higher confidence in the prediction. When they disagree, it may indicate the child is growing faster or slower than their genetic potential suggests — which could be normal variation, differences in pubertal timing, or worth discussing with a pediatrician.
Height Predictor FAQ
How accurate is this height predictor?
The growth curve projection typically has a standard error of about 5–6 cm for younger children, narrowing as the child approaches adult height. The mid-parental method has a standard error of about 8.5 cm. Neither method accounts for early or late puberty, which is the biggest source of prediction error. For the most accurate prediction, a pediatric endocrinologist can order a bone age X-ray.
What age range does this predictor work for?
The growth curve projection requires CDC stature-for-age data, valid for children ages 2 to 17. For children under 2, height prediction is unreliable because too much growth remains. The mid-parental method works at any age but is most useful when combined with the growth projection.
Why are the two predictions different?
The growth curve projection reflects your child's actual growth trajectory, while mid-parental height reflects genetic potential. A child who is taller than expected for their parents may have a growth projection above their mid-parental target — this is common when one parent is significantly taller or when the child is an early maturer. Conversely, a late bloomer may project below their genetic target temporarily.
Does this calculator account for puberty timing?
No — neither method used here accounts for early or late puberty, which is the single biggest factor in height prediction accuracy during the adolescent years. A child who enters puberty early may appear to be on track for a tall adult height but then stop growing earlier. Bone age assessment is the best way to account for pubertal timing.
My child is very short/tall for their age. Is the prediction still useful?
The growth projection is most reliable when a child is tracking consistently along a percentile curve. For children at the extremes (below 3rd or above 97th percentile), the prediction carries more uncertainty. If your child is significantly shorter or taller than expected for your family, consult a pediatric endocrinologist who can assess whether the growth pattern is normal.
How does this compare to the Khamis-Roche method?
The Khamis-Roche method is a regression-based prediction that combines the child's current height, weight, and parent heights using published coefficients. It is considered one of the most accurate non-invasive methods. Our dual-method approach provides similar information from a different angle — growth curve projection is trajectory-based while Khamis-Roche is regression-based. Both have similar accuracy ranges.