# What will my child’s adult height be?

Predicts a child’s adult height from the parents’ heights with Tanner’s mid-parental method: (father + mother + 13 cm) ÷ 2 for a boy, − 13 cm for a girl, ± 8.5 cm.

- Page: https://www.acalculator.org/health/height-calculator
- JSON spec: https://www.acalculator.org/health/height-calculator.json
- Version: 208d564acfb0

## Default answer

Example with the default inputs (Child’s sex Boy, Father’s height 5 ft 10 in, Mother’s height 5 ft 4 in): The predicted adult height is 69.6 in (5 ft 9.6 in), likely between 66.2 in and 72.9 in.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| sex | Child’s sex | The child’s sex, which moves the target up or down by 6.5 cm. |
| father | Father’s height | The biological father’s adult height. |
| mother | Mother’s height | The biological mother’s adult height. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| target | Predicted adult height | The mid-parental target height: (father + mother ± 13 cm) ÷ 2. |
| feetInches | In feet and inches, or metres | The predicted height in feet and inches (US) or in metres (Metric). |
| targetCm | In centimetres | The predicted height in centimetres. |
| low | Likely range from | The low end of the target range: the prediction − 8.5 cm. |
| high | Likely range up to | The high end of the target range: the prediction + 8.5 cm. |

## Method

Predicted adult height = (father’s height + mother’s height + 13 cm) ÷ 2 for a boy, or − 13 cm for a girl; range ± 8.5 cm.

## Assumptions

- Men are on average about 13 cm taller than women, so a parent’s height is moved by 13 cm to the child’s sex before averaging.
- The range of 8.5 cm either side is Tanner’s target range, about the 3rd to 97th centile for children of these parents.
- The parents are the biological parents, and the child grows in good health and nutrition.
- This is a rough guide for families, not a medical prediction. A pediatrician can use growth charts and bone age for more.

## Worked examples

1. sex = male, father = 1.778, mother = 1.6256 gives target = 1.7668, low = 1.6818, high = 1.8518. Source: Tanner et al. 1970 (mid-parental height ± 8.5 cm); hand calculation in content.mdx.
2. sex = female, father = 1.778, mother = 1.6256 gives target = 1.6368, low = 1.5518, high = 1.7218. Source: Tanner et al. 1970; hand calculation in content.mdx.
3. sex = female, father = 1.8, mother = 1.65 gives target = 1.66, targetCm = 1.66. Source: Tanner et al. 1970; hand calculation in content.mdx.
4. sex = male, father = 1.8796, mother = 1.7018 gives target = 1.8557, high = 1.9407. Source: Tanner et al. 1970; hand calculation in content.mdx.

## FAQ

### How can I predict my child's adult height?

A common method is the mid-parental height (Tanner, 1970). Add the parents' heights, add 13 cm (5 inches) for a boy or take away 13 cm for a girl, and divide by 2. With a 5 ft 10 in father and a 5 ft 4 in mother, a boy's prediction is about 5 ft 9.6 in and a girl's about 5 ft 4.4 in.

### Why add or take away 13 cm?

On average, adult men are about 13 cm (5 inches) taller than adult women. Moving one parent's height by that amount puts both parents on the same scale as the child before averaging.

### How accurate is the prediction?

It is a rough guide. Tanner's target range is 8.5 cm (about 3.3 inches) either side of the prediction, about the 3rd to 97th centile, so two children of the same parents can end up quite far apart. Nutrition, health and puberty timing also matter.

### Is there a more accurate method?

Methods that also use the child's own height, weight and age, or an X-ray of the hand to find bone age, can be more precise for a given child. A pediatrician can use these and the growth charts to follow how a child is growing.

### Does this work for adopted children?

No. The method uses the biological parents' heights, because it is built on how height runs in families.

### Can I enter heights in centimetres?

Yes. Switch each height to cm or m, or use the Metric switch. The result is shown in inches, feet and inches, and centimetres, or in centimetres and metres with the Metric switch.

## Sources

- Tanner JM, Goldstein H, Whitehouse RH. Standards for children's height at ages 2-9 years allowing for heights of parents. Arch Dis Child. 1970;45(244):755-762. https://doi.org/10.1136/adc.45.244.755
- Harvard Medical School, Home Parenteral Nutrition program. Linear growth: mid-parental height (father + mother ± 13) ÷ 2, citing Tanner 1970. https://hpn.hms.harvard.edu/linear-growth
- Centers for Disease Control and Prevention. Growth charts. https://www.cdc.gov/growthcharts/