Height Predictor — How Tall Will My Child Be?

Our free height predictor estimates a child's predicted adult height using the same growth reference data that pediatricians rely on — the CDC 2000 growth charts and WHO Child Growth Standards. Enter a child's current age and height, and optionally the parents' heights, to receive a personalized adult height estimate with a confidence range.

How to Use the Height Predictor

1. Select sex — male and female growth curves differ significantly, especially after age 10 when puberty begins.
2. Set age and current height — use the sliders to enter the child's current age (in years and months) and measured height in cm or feet/inches.
3. Add parent heights (optional) — including both parents' heights blends the growth-percentile estimate with the Tanner mid-parental height formula, improving accuracy.
4. Add additional factors (optional) — diet quality, puberty timing, preterm birth status, and chronic health conditions each carry evidence-based adjustments applied on top of the baseline prediction.

The predicted adult height and confidence range update live as you adjust any input.

How Does Child Height Prediction Work?

The calculator uses the LMS method (Box-Cox power transformation), the statistical framework underlying both the CDC 2000 and WHO growth chart reference tables. Every child's height is converted to a z-score relative to other children of the same age and sex. That z-score is projected forward to the adult reference age (20 years), yielding a predicted height alongside a ±1 SD range.

When parent heights are provided, the calculator blends (50/50) the child's current growth z-score with the mid-parental z-score derived from the Tanner-Whitehouse formula. This dual-signal approach is more accurate than either method alone.

The Mid-Parental Height Method (Tanner-Whitehouse)

The mid-parental height method calculates a child's genetic height target based on the average of both parents' heights, with a sex correction factor of ±6.5 cm:

• Boys: (Father's height + Mother's height + 13 cm) ÷ 2
• Girls: (Father's height + Mother's height − 13 cm) ÷ 2

The result is the genetic target height. The typical range is ±8.5 cm, covering approximately 95% of outcomes.

What Factors Affect a Child's Adult Height?

Genetics accounts for roughly 60–80% of a person's final adult height. The remaining 20–40% is shaped by:

Nutrition and Diet Quality

Adequate protein, zinc, vitamin D, calcium, and iron are essential for linear bone growth. Children with consistently poor diets may fall short of their genetic height potential by 3–5 cm or more.

Puberty Timing

Children who enter puberty earlier than peers experience an earlier growth spurt but also earlier growth plate closure, often resulting in a shorter adult height. Late developers grow for longer and frequently reach or exceed their genetic target.

Preterm Birth

Children born prematurely (before 37 weeks) may finish slightly shorter on average than full-term peers. Very preterm birth (before 32 weeks) carries a larger average deficit of approximately 1–2 cm.

Chronic Health Conditions

Several ongoing conditions suppress linear growth, including long-term corticosteroid use, untreated coeliac disease, and other systemic illnesses. Effective treatment often allows partial or full catch-up growth.

About Our Growth Data: CDC 2000 & WHO Standards

• WHO Child Growth Standards (2006) — used for children aged 0–24 months. Based on a multicentre international study representing prescriptive standards of healthy growth.
• CDC 2000 Growth Charts — used for children aged 2–20 years. Based on nationally representative US survey data (NHANES), widely used by American pediatricians.

Data sources: CDC 2000 & WHO Child Growth Standards. For informational purposes only — not a substitute for medical advice.

Frequently Asked Questions

How tall will my child be as an adult?
A child's adult height is primarily determined by genetics (about 60–80%), with the remainder shaped by nutrition, sleep, health, and puberty timing.

How accurate is a height predictor?
Growth chart percentile tracking combined with mid-parental height is the most accurate non-clinical method, with a typical standard deviation of ±5 cm.

At what age can you predict a child's final adult height?
By age 8–10, growth percentile tracking is reasonably stable. By 12–14, estimates are typically within 2–3 cm of final height.

Does nutrition affect how tall a child will be?
Yes. Chronic nutritional deficiency can reduce final height by 3–5 cm or more.

When do boys stop growing?
Most boys stop growing between ages 17 and 20. The peak growth spurt occurs around age 13–14.

When do girls stop growing?
Most girls stop growing between ages 15 and 17, roughly 2–3 years after their first menstrual cycle.

How much of height is determined by genetics?
Twin and family studies estimate genetics accounts for 60–80% of adult height variation.

Do boys grow taller than girls on average?
Yes. The average adult male in the US is ~175.4 cm (5′9″) versus ~161.7 cm (5′4″) for females.

What is the CDC LMS growth chart method?
The LMS method models height distribution using three age-specific parameters — L (Box-Cox power), M (median), and S (coefficient of variation) — enabling precise z-score conversion at any age.