# Child Height Predictor (Adult Height Calculator)

URL: https://speedycalculator.com/calculators/health/height/
Last updated: 2026-10-30

> The child height predictor estimates how tall a child will be as an adult with the mid-parental height method (parents' heights adjusted for the child's sex) and the "twice the height at age 2" rule, with the typical target range.

## Inputs

- Sex
- Father's height (cm, in, m, ft, mm)
- Mother's height (cm, in, m, ft, mm)
- Child's height at 2 years (boys) or 18 months (girls) – optional (cm, in, m, ft, mm)

## Results

- Predicted adult height (mid-parental)
- Target range from
- Target range to
- Prediction from early height

## Formula

```
Mid-parental height: boys = (father + mother + 13 cm) ÷ 2; girls = (father + mother − 13 cm) ÷ 2
Target range ≈ mid-parental height ± 8.5 cm
Rule of thumb: adult height ≈ 2 × height at age 2 (boys) or at 18 months (girls)
```

## Explanation

Height is about 80% genetic, so parents' heights are the best simple predictor. Nutrition, health and the timing of puberty affect where in the target range a child ends up. Bone-age X-rays give more precise predictions.

### How to use the Child Height Predictor

- **Sex**
- **Father's height**
- **Mother's height**
- **Child's height at 2 years (boys) or 18 months (girls) – optional**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter both parents' heights and the child's sex, and optionally the child's height at 2 years (boys) or 18 months (girls).

### Inputs explained

FieldWhat to enterSexChoose one: Male, FemaleFather's heightUnits: cm, in, m, ft, mmMother's heightUnits: cm, in, m, ft, mmChild's height at 2 years (boys) or 18 months (girls) – optionalUnits: cm, in, m, ft, mm

### What each result means

- **Target range from** = [Predicted adult height (mid-parental)] - 8.5
- **Target range to** = [Predicted adult height (mid-parental)] + 8.5

### Example values

How the main result changes when **Father's height** changes and everything else stays at the example values above:

Father's height (cm)Predicted adult height (mid-parental) (cm)89133.5133.5155.8178178222.5200.3
*Health note: this calculator is for education and screening only and is not a diagnosis or treatment advice. Discuss your results with a qualified clinician.*

## Worked example

Inputs — Sex: Male; Father's height: 178 cm; Mother's height: 165 cm; Child's height at 2 years (boys) or 18 months (girls) – optional: 0 cm.

Results — **Predicted adult height (mid-parental) = 178 cm**; Target range from = 169.5 cm; Target range to = 186.5 cm; Prediction from early height = 178 cm.

## Key terms

- **Mid-parental height**: Average of the parents' heights adjusted for sex.

## FAQ

**How accurate is mid-parental height?**
About 95% of children end up within ±8.5 cm of it.

**Can my child grow taller than predicted?**
Yes – nutrition, sleep and health all play a part, and genetics is not exact.

**When do children stop growing?**
Usually around 14–16 for girls and 16–18 for boys.


## Sources

- [Tanner JM et al. Standards for children's height at ages 2–9 years allowing for height of parents. Arch Dis Child, 1970](https://pubmed.ncbi.nlm.nih.gov/5440182/)