Child Height Predictor

The Child Height Predictor estimates how tall a child will be as an adult using the mid-parental height method — the simple, widely used clinical formula that combines the mother's and father's heights with a sex adjustment. Beyond a single number, this tool shows the prediction's 95% range on a visual height ruler, compares your child against mum and dad with scaled family figures, and tells you what adult-height percentile the prediction falls into.

What Is the Mid-Parental Height Method?

The mid-parental (or "target height") method was popularized by the paediatric growth researcher J. M. Tanner. It assumes that a child's adult height tends to land near the average of the two parents, shifted up for boys and down for girls to reflect the roughly 13 cm (5 inch) average difference between adult men and women. It only needs the two parents' heights, so it can be used at any age — even before a child is born.

Child Height Prediction Formula

The calculation takes two short steps: average the parents, then apply the sex adjustment.

In imperial units the sex adjustment is 5 inches (added for boys, subtracted for girls) and the range is about 3.3 inches either side of the prediction.

Worked Example

Suppose dad is 180 cm and mum is 165 cm, and the child is a boy:

• Average the parents: (180 + 165) ÷ 2 = 172.5 cm
• Add the boy adjustment: 172.5 + 6.5 = 179 cm (about 5'10")
• 95% range: 170.5 cm to 187.5 cm (about 5'7" to 6'2")

For a girl with the same parents, you would subtract 6.5 cm instead, giving a prediction of 166 cm (about 5'5").

Mid-Parental Height Quick Reference (Metric)

How Accurate Is the Prediction?

The mid-parental method is a sound starting estimate, but it is a probability, not a promise. About 95% of children reach an adult height within roughly 8.5 cm (3.3 inches) of the prediction, which is why this tool always shows the range, not just a single figure. The method works best when both parents reached their own genetic height potential — if a parent's growth was limited by childhood illness or poor nutrition, the prediction may run low.

What Affects a Child's Final Height?

How to Use This Calculator

1. Choose the child's gender: Select Boy or Girl — the sex adjustment differs by about 13 cm.
2. Choose your units: Pick Imperial (feet and inches) or Metric (centimetres).
3. Enter both parents' heights: Add the father's height and the mother's height.
4. Click Predict Height: The tool instantly shows the predicted adult height and its 95% range.
5. Review the visuals: See the height ruler, the family figure comparison, and the adult-height percentile.

Frequently Asked Questions

How is a child's adult height predicted from the parents?

The mid-parental height method averages the parents' heights and then adjusts for the child's sex. For a boy: predicted height = (father's height + mother's height + 13 cm) ÷ 2. For a girl: predicted height = (father's height + mother's height − 13 cm) ÷ 2. The 13 cm term is the average adult height difference between men and women.

How accurate is the mid-parental height method?

It is a useful estimate, not a guarantee. About 95% of children reach an adult height within roughly 8.5 cm (3.3 inches) of the mid-parental prediction. Nutrition, health, sleep, hormones, and genetics beyond the parents all influence the final outcome.

At what age can I predict my child's adult height?

The mid-parental method only needs the parents' heights, so it can be used at any age, even before birth. Other methods that use the child's current height and bone age become more accurate from around age 2 to 4 onward.

Can a child be taller than both parents?

Yes. The prediction is an average expectation with a wide range. Many children end up taller or shorter than both parents because of genetic variation, improved nutrition across generations, and other factors. The 95% range shows how much variation is normal.

Does the mid-parental method work for both boys and girls?

Yes. The only difference is the sex adjustment: 13 cm is added for boys and subtracted for girls before averaging, which reflects the average adult height gap between men and women.