Height Calculator
Predict your child's future adult height using two scientific methods: the Khamis-Roche Height Predictor and the Mid-Parental Height Calculator.
What is Height Prediction?
Height prediction is the scientific estimation of a child's final adult height based on various factors including genetics (parental heights), current height and weight, age, and sex. While genetics plays a major role in determining height (accounting for about 60-80% of height variation), environmental factors like nutrition, health, and physical activity also influence growth.
Our calculator offers two scientifically-validated methods to predict your child's adult height:
- Khamis-Roche Method: The most accurate non-bone-age method, using child's current measurements
- Mid-Parental Height Method: A simpler calculation based solely on parents' heights
The Khamis-Roche Method
The Khamis-Roche method was developed in 1994 by Dr. Harry Khamis and Dr. Alex Roche at Wright State University. It is considered the most accurate method for predicting adult height without requiring bone age assessment (X-ray of the hand).
The Formula
Hadult = β + (ah × hchild) + (aw × wchild) + (ap × hmidparent)
Where:
- β = Intercept coefficient (varies by age and sex)
- ah = Child's height coefficient
- aw = Child's weight coefficient
- ap = Midparent height coefficient
- hmidparent = (Mother's height + Father's height) ÷ 2
Accuracy
- For boys: ±2.1 inches (5.3 cm) margin of error
- For girls: ±1.7 inches (4.3 cm) margin of error
- 90% accuracy rate when used correctly
Limitations
- Developed primarily for Caucasian children (may be less accurate for other ethnicities)
- Only valid for ages 4-17.5 years
- Assumes normal growth without medical conditions affecting height
The Mid-Parental Height Method
The Mid-Parental Height method (also called the Tanner method) is a simpler calculation that estimates a child's adult height based solely on the heights of both biological parents. While less accurate than the Khamis-Roche method, it provides a quick estimate when the child's current measurements aren't available.
The Formulas
For Girls:
Height = (Mother's height + Father's height − 13 cm) ÷ 2
For Boys:
Height = (Mother's height + Father's height + 13 cm) ÷ 2
The 13 cm (approximately 5 inches) adjustment accounts for the average height difference between adult males and females.
Accuracy
The mid-parental height method has a margin of error of approximately ±4 inches (10 cm). This larger margin exists because the method doesn't account for the child's current growth status.
Factors Affecting Height
Genetic Factors (60-80%)
- Parental heights
- Family history of growth patterns
- Ethnic background
- Genetic variations affecting growth hormones
Environmental Factors (20-40%)
- Nutrition quality
- Sleep patterns
- Physical activity
- Overall health status
- Hormonal balance
- Socioeconomic conditions
Average Height by Age (US CDC Data)
| Age | Boys (cm) | Boys (ft'in") | Girls (cm) | Girls (ft'in") |
|---|---|---|---|---|
| 4 years | 103 | 3'5" | 101 | 3'4" |
| 6 years | 116 | 3'10" | 115 | 3'9" |
| 8 years | 128 | 4'2" | 127 | 4'2" |
| 10 years | 138 | 4'6" | 138 | 4'6" |
| 12 years | 149 | 4'11" | 152 | 5'0" |
| 14 years | 164 | 5'5" | 160 | 5'3" |
| 16 years | 173 | 5'8" | 163 | 5'4" |
| 18 years (Adult) | 176 | 5'9" | 163 | 5'4" |
Frequently Asked Questions
How accurate is this height calculator?
The Khamis-Roche method has a 90% accuracy rate with a margin of error of ±2.1 inches for boys and ±1.7 inches for girls. The mid-parental method has a larger margin of ±4 inches but is useful for quick estimates.
At what age can I predict my child's height?
The Khamis-Roche method works for children aged 4 to 17.5 years. For younger children, height predictions are less reliable due to high variability in early growth patterns.
Why is my child's weight needed for the prediction?
Weight provides important information about a child's nutritional status and growth trajectory. Children who are heavier for their age may be further along in their growth, affecting the prediction.
Can medical conditions affect my child's predicted height?
Yes. Growth hormone deficiencies, thyroid disorders, chronic illnesses, and other medical conditions can significantly affect height. These predictions assume normal, healthy growth. Consult a pediatrician if you have concerns about your child's growth.
Why are there different predictions for different ethnicities?
The Khamis-Roche method was developed using data from Caucasian American children. Different ethnic populations may have different growth patterns, so the predictions may be less accurate for children of other backgrounds.
When do children stop growing?
Girls typically stop growing around age 14-16, while boys continue growing until about 16-18 years old. However, some individuals may continue growing slightly into their early 20s.