Will my kids be tall?

This calculator uses the mid-parental height formula (Tanner, Goldstein & Whitehouse, Arch Dis Child 1970), which predicts adult height within ±3.5 inches for most children. It's genetics-only — your heights account for roughly 60–80% of your child's final height. Nutrition, sleep, and puberty timing can each shift the result by an additional inch or two.

It uses the Tanner mid-parental height formula: for boys, predicted height = (mother's height + 5 inches + father's height) ÷ 2. For girls, predicted height = (mother's height + father's height − 5 inches) ÷ 2. The ±5 inch offset accounts for the typical height difference between adult men and women. This is the most widely used clinical formula when a child's own measurements aren't yet available.

Yes. Once your child is age 4 or older, our Full Height Predictor uses the Khamis-Roche method, which factors in your child's current height, weight, and age — significantly improving accuracy to ±2.2 inches for boys and ±1.7 inches for girls. This is the same approach pediatric endocrinologists use for non-invasive height prediction.

Tall parents strongly increase the odds, but genetics isn't a guarantee. The mid-parental height represents the genetic ceiling/baseline, but environmental factors (nutrition, sleep, chronic illness, stress) can prevent a child from reaching their genetic potential. Conversely, optimal environment usually brings a child close to their genetic target.

Because this formula uses only parental heights — no current measurements of your child. Genetics explain 60–80% of height variation; the remaining 20–40% comes from environment and timing factors that can't be predicted in advance. The full Khamis-Roche method (used in our Height Predictor) narrows the range to ±2.2 inches by incorporating the child's current height and weight.

The Tanner formula was validated primarily on Western European populations. Some studies suggest slight adjustments may improve accuracy for other ethnic groups (who have different average adult heights and height dimorphism), but the formula remains widely used cross-culturally as a practical estimate. For a personalized assessment, consult a pediatrician.

Most girls reach adult height by age 15–17, and most boys by age 17–21. Growth plates — the cartilage zones that produce new bone — fuse near the end of puberty. Our Growth Plate Status quiz can help estimate where your child currently stands in the growth process.