PredictHeight

CDC growth charts · Fels Longitudinal Study · Tanner 1970

How tall will they actually be?

The free answer uses the child’s growth curve, both parents, and Khamis–Roche when you add weight. Predictions are estimates. Stretching does not lengthen bones.

  • ~80% genetics
  • ±5 cm typical KR error
  • 0 cm from stretching bones
A child standing against a wall while a parent marks their height.
Photo: Ian Taylor / Pexels

Growing child

The kid
The parents

The number is free. The Full Growth Report ($4.99) adds the method comparison, growth window, and a printable card.

1. CDC percentile

We place the child on the official U.S. stature-for-age chart (ages 2–20) using LMS z-scores, then project that percentile to age 20.

2. Parental genetics

Tanner’s mid-parental formula and Luo’s 1998 regression. Heritability of height is about 80% in well-fed populations.

3. Khamis–Roche

When weight is entered (ages 4–17.5), we use the 1995-corrected coefficients from Pediatrics. Typical 90% error: about ±5 cm.