Child Height Predictor
Predict a child's adult height from the parents' heights using the mid-parental (target height) formula.
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What this tool does
Predict a child's adult height from the parents' heights using the mid-parental (target height) formula. Mid-parental (target height) formula only. The Khamis–Roche method additionally requires the child's current height, weight and its published age/sex coefficient table; those coefficients are not embedded here, so no Khamis–Roche mode is offered rather than approximating them. Genetics, nutrition and health make individual outcomes vary widely.
How to use the Child Height Predictor
- Enter or select father's height in in.
- Enter or select mother's height in in.
- Enter or select child's sex.
- Read the calculated result; change any measurement to compare alternatives.
Formula
mid-parental height: boy = (father + mother + 5 in) / 2; girl = (father + mother − 5 in) / 2; usual range ±3.3 in (8.5 cm, ~±2 SD)
- father
- Father's height (in, before metric conversion)
- mother
- Mother's height (in, before metric conversion)
- sex
- Child's sex
Mid-parental (target height) formula only. The Khamis–Roche method additionally requires the child's current height, weight and its published age/sex coefficient table; those coefficients are not embedded here, so no Khamis–Roche mode is offered rather than approximating them. Genetics, nutrition and health make individual outcomes vary widely.
Worked example
For child height predictor, the following measurements illustrate the exact method: Father's height: 69; Mother's height: 64; Child's sex: boy.
Inputs
- Father's height69 in
- Mother's height64 in
- Child's sexBoy
Result
- Predicted adult height (mid-parental)69 in
- Usual range (±3.3 in)65.7 – 72.3 in
Results explained
- Predicted adult height (mid-parental)
- Predicted adult height (mid-parental) from the formula above, expressed in in before metric conversion. Mid-parental (target height) formula only. The Khamis–Roche method additionally requires the child's current height, weight and its published age/sex coefficient table; those coefficients are not embedded here, so no Khamis–Roche mode is offered rather than approximating them. Genetics, nutrition and health make individual outcomes vary widely.
- Usual range (±3.3 in)
- Usual range (±3.3 in) from the formula above. Mid-parental (target height) formula only. The Khamis–Roche method additionally requires the child's current height, weight and its published age/sex coefficient table; those coefficients are not embedded here, so no Khamis–Roche mode is offered rather than approximating them. Genetics, nutrition and health make individual outcomes vary widely.
Frequently asked questions
For a boy: add 5 inches to the sum of both parents' heights and halve it. For a girl: subtract 5 inches before halving. The 5-inch adjustment reflects the average adult height difference between men and women.
About 95% of children finish within roughly ±3.3 inches (8.5 cm) of the mid-parental target. It is a population guide — individual genetics, nutrition and health shift outcomes.
Khamis–Roche (1994) improves prediction using the child's current height, weight, age and mid-parent height with published age/sex coefficients. Those coefficient tables could not be embedded faithfully here, so this tool offers the mid-parental formula only, and says so rather than guessing coefficients.
Yes — a child tall or short for their parents at age 8 carries information beyond parent heights (that is what Khamis–Roche adds). Paediatricians also track the child's own growth curve and bone age when it matters clinically.
Yes. Children inherit a shuffled mix of height genes from extended family, and the ±3.3 in band is wide. Well outside it, or a growth curve crossing percentiles, is worth a paediatric conversation.