# Child Height Predictor

> The most common way to predict a child's adult height is the average of both parents' heights, plus 5 inches for a boy or minus 5 inches for a girl. Enter the parents' heights, or your toddler's height at 2, to get an estimate and its range.

- Interactive calculator: https://www.leoella.com/tools/child-height-predictor
- Plain-text version: https://www.leoella.com/tools/child-height-predictor.md
- Category: Baby & Toddler
- Publisher: Leo&Ella (https://www.leoella.com)
- Last reviewed: October 19, 2026

## How it works

From the parents' heights, the calculator adds the mother's and father's adult heights, adds 5 inches (13 cm) for a boy or subtracts it for a girl, and divides by 2: the mid-parental method that Mayo Clinic and the AAP describe. It shows a likely range of 4 inches (10 cm) either side of that estimate, the AAP's margin of error. From a toddler's height, it doubles a boy's height at 2 years or a girl's at 18 months, the AAP's rule of thumb, and gives no range. Heights go in as feet and inches or centimeters, and results are rounded to the nearest half inch or whole centimeter.

## Key facts

- Mayo Clinic describes the mid-parental height method for predicting a child's adult height: add the mother's and father's heights, add 5 inches (13 centimeters) for a boy or subtract 5 inches (13 centimeters) for a girl, and divide by 2. [2]
- The AAP describes the mid-parental height formula as a very rough estimate, with a margin of error of about 4 inches up or down. [1]
- Using Mayo Clinic's mid-parental formula, a mother of 5 ft 3 in and a father of 5 ft 9 in give an estimated adult height of 5 ft 8½ in for a son and 5 ft 3½ in for a daughter. [2]
- The AAP calls doubling a boy's height at age 2, or a girl's height at 18 months, a popular rule of thumb rather than a medically validated way to predict adult height. [1]
- The AAP says studies suggest about 60% to 70% of differences in height are determined by the parents' heights; nutrition, sleep, physical activity, health conditions and hormones account for the rest. [1]
- According to the AAP, the most accurate way to predict a child's adult height combines their current height with a bone age assessment, a hand and wrist X-ray that a doctor orders. [1]

## Reference data

### Mid-parental height: worked examples

(Mother + father + 5 in) ÷ 2 for a boy, (mother + father − 5 in) ÷ 2 for a girl; 13 cm instead of 5 in for centimeters. The range is the AAP's margin of error, about 4 in (10 cm) either way. Results are rounded to the nearest half inch or whole centimeter.

| Parents | Child | Estimate | Likely range |
| --- | --- | --- | --- |
| Mother 5 ft 3 in (63 in), father 5 ft 9 in (69 in) | Son | 5 ft 8½ in (68.5 in) | 5 ft 4½ in to 6 ft 0½ in |
| Mother 5 ft 3 in (63 in), father 5 ft 9 in (69 in) | Daughter | 5 ft 3½ in (63.5 in) | 4 ft 11½ in to 5 ft 7½ in |
| Mother 160 cm, father 175 cm | Son | 174 cm | 164 cm to 184 cm |
| Mother 160 cm, father 175 cm | Daughter | 161 cm | 151 cm to 171 cm |

### Estimated adult height of a son, by parents' heights

| Mother (row) / father (column) | 5 ft 6 in | 5 ft 8 in | 5 ft 10 in | 6 ft 0 in | 6 ft 2 in |
| --- | --- | --- | --- | --- | --- |
| 5 ft 0 in | 5 ft 5½ in | 5 ft 6½ in | 5 ft 7½ in | 5 ft 8½ in | 5 ft 9½ in |
| 5 ft 2 in | 5 ft 6½ in | 5 ft 7½ in | 5 ft 8½ in | 5 ft 9½ in | 5 ft 10½ in |
| 5 ft 4 in | 5 ft 7½ in | 5 ft 8½ in | 5 ft 9½ in | 5 ft 10½ in | 5 ft 11½ in |
| 5 ft 6 in | 5 ft 8½ in | 5 ft 9½ in | 5 ft 10½ in | 5 ft 11½ in | 6 ft 0½ in |
| 5 ft 8 in | 5 ft 9½ in | 5 ft 10½ in | 5 ft 11½ in | 6 ft 0½ in | 6 ft 1½ in |

### Estimated adult height of a daughter, by parents' heights

| Mother (row) / father (column) | 5 ft 6 in | 5 ft 8 in | 5 ft 10 in | 6 ft 0 in | 6 ft 2 in |
| --- | --- | --- | --- | --- | --- |
| 5 ft 0 in | 5 ft 0½ in | 5 ft 1½ in | 5 ft 2½ in | 5 ft 3½ in | 5 ft 4½ in |
| 5 ft 2 in | 5 ft 1½ in | 5 ft 2½ in | 5 ft 3½ in | 5 ft 4½ in | 5 ft 5½ in |
| 5 ft 4 in | 5 ft 2½ in | 5 ft 3½ in | 5 ft 4½ in | 5 ft 5½ in | 5 ft 6½ in |
| 5 ft 6 in | 5 ft 3½ in | 5 ft 4½ in | 5 ft 5½ in | 5 ft 6½ in | 5 ft 7½ in |
| 5 ft 8 in | 5 ft 4½ in | 5 ft 5½ in | 5 ft 6½ in | 5 ft 7½ in | 5 ft 8½ in |

### The doubling rule (the AAP's rule of thumb)

Twice a boy's height at 2 years or a girl's at 18 months. The AAP calls it a popular rule of thumb, not a medically validated prediction, so the calculator gives no range for it. The heights below are example inputs.

| Child | Measured at | Height then | Doubled |
| --- | --- | --- | --- |
| Boy | 24 months | 34 in | 5 ft 8 in |
| Boy | 24 months | 86 cm | 172 cm |
| Girl | 18 months | 31.5 in | 5 ft 3 in |
| Girl | 18 months | 80 cm | 160 cm |

## Frequently asked questions

### How can I predict how tall my child will be?

The most common home method is the mid-parental height: add the mother's and father's heights, add 5 inches (13 cm) for a boy or subtract 5 inches for a girl, and divide by 2. Mayo Clinic and the AAP both describe it, and the AAP gives a margin of error of about 4 inches up or down.

### Does doubling a 2-year-old's height work?

Doubling a boy's height at age 2, or a girl's at 18 months, gives a rough estimate because toddlers have done about half their growing by then. The AAP calls it a popular rule of thumb rather than a medically validated prediction tool, and notes no research shows how accurate it is.

### What is the most accurate way to predict adult height?

According to the AAP, the most accurate method combines a child's current height with a bone age assessment, an X-ray of the hand and wrist that a doctor orders. Formulas you can use at home are rough estimates.

### How much of height is genetic?

Most of it. The AAP says studies suggest about 60% to 70% of differences in height are determined by the parents' heights. The rest comes from nutrition, sleep, physical activity, health conditions, hormones and other influences.

### Why does the formula add or subtract 5 inches?

It puts both parents on the same scale as the child before averaging: for a son, 5 inches (13 cm) is added to the mother's height; for a daughter, 5 inches is taken off the father's height. Adding or subtracting it after summing both heights gives the same result.

### When should I worry about my child's height?

Talk with your pediatrician if your child seems to be growing much faster or slower than other children, or is drifting across lines on their growth chart. The AAP notes growth problems are often easier to treat when found early, before the growth plates close after puberty.

## Sources

1. [AAP (HealthyChildren.org): Predicting a Child's Adult Height](https://www.healthychildren.org/English/health-issues/conditions/Glands-Growth-Disorders/Pages/Predicting-a-Childs-Adult-Height.aspx)
2. [Mayo Clinic: Child growth: Can you predict adult height?](https://www.mayoclinic.org/healthy-lifestyle/childrens-health/expert-answers/child-growth/faq-20057990)

## About this page

This is general information for parents, not medical advice; a doctor, midwife or pediatrician who knows the family should guide individual decisions. The calculator runs in the visitor's browser and stores nothing they enter. When quoting this page, cite "Child Height Predictor, Leo&Ella" and link https://www.leoella.com/tools/child-height-predictor.