Health • Height

Height Calculator

Predict a child’s adult height with Tanner mid-parent target (±8.5 cm) and Khamis-Roche (without bone age) using age, current height, weight and parents’ heights.

Direct Answer

The Tanner mid-parental method estimates child adult height by averaging the biological parents heights and adjusting for biological sex: add 2.5 inches (6.5 cm) for boys or subtract 2.5 inches (6.5 cm) for girls, with an expected range of ±4 inches.

Child’s sex

Boy Girl

Age (years, decimal e.g., 10.5)Child height

Child weight

Father height

Mother height

Tanner — mid-parent target

—

Khamis-Roche (without bone age)

—

Details

Tanner: Boys (Father+Mother+13)/2, Girls (Father+Mother−13)/2 ±8.5 cm. Khamis-Roche (1994 corrected 1995, Fels): B₀+b₁H+b₂W+b₃MP (H in, W lb, MP avg). 68% margin ±5.6 cm boys / ±4.3 cm girls. Valid 4–17.5y both sexes (erratum).

How to use

1Choose the child’s sex and decimal age (e.g., 10.5 for 10y6m). Age range for Khamis-Roche is 4–17.5 boys, 4–16.5 girls.
2Enter current height and weight (switch kg/lb, cm/in) and both parents’ heights.
3See Tanner target + range and Khamis-Roche prediction with 68% margin (±5.6 cm boys / ±4.3 cm girls).

Formulas

Tanner: Boys (Father+Mother+13)/2 • Girls (Father+Mother−13)/2 • Khamis-Roche: B₀+b₁H(in)+b₂W(lb)+b₃MP(in)

Variable	Name	Meaning & Example
H_father	Fathers Height	Biological fathers adult height (180 cm (5 ft 11 in))
H_mother	Mothers Height	Biological mothers adult height (165 cm (5 ft 5 in))
H_target	Predicted Height	Estimated target adult stature (±8.5 cm) (179 cm)

Tanner is simple and valid at any age (≈95% within ±10 cm). Khamis-Roche 1994 is more accurate at 4–14y using regression without an X-ray; coefficients are sex/age-specific and interpolated for fractional ages.

Examples

Boy, 10y, 140cm, 35kg, father 175cm, mother 162cm

Tanner 175 cm (Range 166.5–183.5) • Khamis-Roche ~174 cm (±5.6) reflecting percentile.

Tanner 175 • Khamis ~174

Girl, 9y, 135cm, 30kg, father 180cm, mother 165cm

Tanner (180+165−13)/2=166 cm • Khamis ~164 cm (±4.3).

Tanner 166 • Khamis ~164

About

The Height Calculator predicts a child's adult height using two established methods: the Tanner mid-parental target and the Khamis-Roche technique, which does not require a bone-age X-ray. Enter the child's sex, age, height, weight, and both parents' heights to receive a predicted adult height with a realistic range. Parents and pediatric care teams use these estimates for routine growth monitoring and to identify children who may fall outside expected ranges. The predictions are statistical estimates with margins of error, and unusual growth patterns should be discussed with a pediatrician.

Frequently asked questions

Why do the two methods differ?

Tanner uses only parents (genetic target). Khamis-Roche blends the child’s current size + weight + parents, so tall-for-age children predict higher.

How accurate is this?

Tanner ±8.5 cm covers most children; Khamis-Roche 68% within ±5.6 cm (boys) / ±4.3 cm (girls), growing to ~±10 cm at 95%. Nutrition, health and timing of puberty also matter.

Can I use it for adults?

No — once growth plates close, height is set. This is for children still growing.

How accurate is the mid-parental height prediction method?

The Tanner mid-parental method accurately predicts adult height within a ±2 standard deviation range (about ±4 inches or ±8.5 cm) for approximately 95% of healthy children.

What factors beyond genetics influence adult height?

Childhood nutrition, adequate sleep (which stimulates human growth hormone secretion), chronic health conditions, and physical activity all interact with genetic potential.

At what age do boys and girls typically stop growing in height?

Girls typically reach their final adult height around age 14 to 16 (approximately 2 years after menarche), while boys generally continue growing until age 16 to 18.

Disclaimer

Educational estimates only, not medical advice. For growth concerns see a pediatrician. Khamis-Roche validated on U.S. reference children.

Calorie Calculator

Daily calorie needs & BMR

Time Calculator

Age & milestone duration calculations

Hours Calculator

Track active hours