How this calculator works
Mid-parental height is a family-based target, using a 13 cm sex adjustment and the AAP target range of plus or minus 10.2 cm. It is not an individual forecast or a guarantee. The separate percentile mode compares present standing height with CDC 2000 sex-specific LMS data. Reference parameters are interpolated between half-month rows. This page does not use Khamis-Roche coefficients, skeletal age, body weight or an assumption that a child will remain on one percentile through adulthood. The result is an estimate for information only and is not medical advice.
Formula
Male target cm = (mother cm + father cm + 13)/2; female target cm = (mother cm + father cm - 13)/2. Target interval = target ± 10.2 cm. CDC z = ((height/M)^L - 1)/(L S), with ln(height/M)/S for L = 0; percentile = normal CDF(z).
Worked example
Parents of 165 cm and 180 cm give a male target of 179 cm, with a range of 168.8 to 189.2 cm. The female target is 166 cm, with a range of 155.8 to 176.2 cm.
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Frequently asked questions
Is target height the child's predicted final height?
It is a broad estimate from parental stature. Puberty timing, health, nutrition and measurement error can change an individual outcome.
Are the percentiles from a fitted approximation?
No. They use the CDC's published L, M and S values. Only values between reference ages are linearly interpolated.
Can I use a baby's lying length?
No. The percentile mode is for standing stature at ages 2 to 20. Infants need a length-for-age reference and an appropriate measurement technique.