Height Calculator

Introduction

The Height Calculator helps you estimate how tall a child may grow to be as an adult. It uses basic information like the child's current age, gender, and the heights of both parents to make a prediction. While no tool can tell you an exact future height, this calculator uses well-known methods that doctors and health experts trust. Height depends on many things, including genetics, nutrition, and overall health. Use this calculator to get a helpful estimate and better understand how body growth works.

How to Use Our Height Calculator

Enter your child's details and both parents' heights to get a predicted adult height. This calculator offers two prediction methods plus a built-in height unit converter.

Method 1: Khamis-Roche Height Predictor — This method gives the most accurate results. It works best for children between the ages of 4 and 17. You will need to fill in the following fields:

Unit System: Choose between US/Imperial (feet and inches, pounds) or Metric (centimeters, kilograms). The calculator will convert your numbers automatically when you switch.

Child's Sex: Select whether the child is male or female. Boys and girls grow at different rates, so this changes the prediction formula.

Child's Age: Enter the child's age in years, from 4.0 to 17.0. You can use decimals for more accuracy — for example, type 8.5 if the child is 8 years and 6 months old. If you need help determining your child's exact age in years and months, our Age Calculator can help.

Child's Current Height: Enter how tall the child is right now. In Imperial mode, type the feet and inches separately. In Metric mode, type the height in centimeters.

Child's Current Weight: Enter the child's weight. Use the dropdown next to the field to pick pounds (lb) or kilograms (kg).

Mother's Height: Enter the biological mother's height in feet and inches or centimeters, depending on the unit system you picked.

Father's Height: Enter the biological father's height in the same way as the mother's height.

Bone Age (Optional): If a doctor has determined the child's bone age from a hand or wrist X-ray, enter the years and months here. This helps adjust the prediction based on skeletal maturity. You can leave this blank if you do not have this information.

Method 2: Mid-Parental Height Formula — This simpler method only needs the parents' heights and the child's sex. It is useful when the child has not been born yet or when you do not have the child's current height and weight. Enter the child's sex, the mother's height, and the father's height to get a predicted adult height with a range of plus or minus 2 inches.

Height Unit Converter: Use this section to quickly convert between feet and inches and centimeters. Type a value in the US fields to see the metric result, or type a centimeter value to see the feet-and-inches result.

Projected Growth Curve: After you complete Method 1, a chart will appear showing your child's projected growth from their current age to age 18, plotted alongside the 50th percentile average. The shaded band on the chart shows the prediction range based on the formula's margin of error.

How Tall Will My Child Be? Understanding Height Prediction

A child's adult height depends on a mix of genetics, nutrition, health, and hormones. While no tool can tell you the exact height your child will reach, height prediction formulas give a solid estimate based on known factors. This calculator uses two well-known methods to predict how tall a child may grow.

Method 1: The Khamis-Roche Method

The Khamis-Roche method is one of the most trusted ways to predict adult height without an X-ray. It was developed in 1994 using data from a long-term growth study called the Fels Longitudinal Study. This method works best for children between the ages of 4 and 17. It takes into account the child's current height, current weight, age, sex, and the heights of both parents. The formula uses special coefficients, or number values, that change depending on the child's age and sex. These coefficients control how much each factor matters at each stage of growth. For example, a 6-year-old's current height matters less than a 15-year-old's, since the younger child still has many years of growing left.

The Khamis-Roche method also provides a margin of error, which means the true adult height usually falls within a range above or below the prediction. For younger children, this range is wider because there is more time for things to change. For older teens, the range is much smaller because most growth is already done.

If a doctor has measured your child's bone age through a hand and wrist X-ray, you can enter that value for an adjusted prediction. Bone age shows how mature a child's skeleton is. A bone age that is ahead of the child's real age may mean growth will stop sooner. A bone age that is behind may mean more growing time remains.

Method 2: The Mid-Parental Height Formula

The mid-parental height method is simpler and only needs the mother's and father's heights. It averages both parents' heights and then adds 2.5 inches for boys or subtracts 2.5 inches for girls. This adjustment accounts for the average height difference between males and females. The result comes with a typical range of plus or minus 2 inches. This method is helpful when you do not have the child's measurements, such as before a baby is born. If you are expecting, our Due Date Calculator can help you track your pregnancy timeline. However, the mid-parental method is less precise than the Khamis-Roche method because it does not consider the child's own growth pattern.

What Affects a Child's Height?

• Genetics: About 60% to 80% of a person's final height is determined by genes inherited from both parents. This is why parental heights are central to every prediction formula.
• Nutrition: A balanced diet rich in protein, calcium, vitamin D, and other nutrients supports healthy bone growth. Poor nutrition during childhood can limit height potential. Tools like our Protein Calculator and Macro Calculator can help ensure your child's diet supports optimal growth.
• Sleep: Growth hormone is released mostly during deep sleep, making quality rest important for growing children. Our Sleep Calculator can help you determine the right amount of sleep for your child's age.
• Health conditions: Chronic illnesses, hormonal disorders such as growth hormone deficiency or thyroid problems, and certain medications can slow or accelerate growth.
• Puberty timing: Children who enter puberty early may have a growth spurt sooner but often stop growing earlier, sometimes resulting in a shorter adult height. Late bloomers may keep growing longer.

How Accurate Are Height Predictions?

The Khamis-Roche method has been shown to predict adult height within about 1 to 2.5 inches for most children. Accuracy improves as the child gets older and closer to their final height. The mid-parental method is a rougher estimate and works best as a general guideline. Neither method accounts for unusual medical conditions, extreme environmental factors, or rare genetic variations. For the most accurate assessment, a pediatrician can combine these formulas with growth chart tracking and, if needed, a bone age X-ray.

Key Terms to Know

• Mid-parental height: The simple average of the mother's and father's heights, used as a baseline genetic indicator.
• Bone age: A measure of skeletal maturity based on an X-ray of the hand and wrist. It may differ from a child's actual age.
• Percentile: A ranking that shows how a child's height compares to other children of the same age and sex. For instance, the 50th percentile means the child is taller than 50% of peers.
• Growth velocity: The rate at which a child grows over time, usually measured in inches or centimeters per year.

Keep in mind that these predictions are estimates, not guarantees. Every child grows at their own pace. Beyond height, you can explore related body metrics like Ideal Body Weight, Lean Body Weight, Body Surface Area (BSA), Waist to Hip Ratio, and Waist to Height Ratio to get a fuller picture of health and development. If you have concerns about your child's growth, talk to a pediatrician or pediatric endocrinologist for personalized guidance.

Frequently Asked Questions

What age range does the Khamis-Roche height predictor work for?

The Khamis-Roche method works best for children between 4 and 17 years old. Outside this range, the formula does not have reliable data to make a good prediction. For children younger than 4, use the mid-parental height method instead.

Can I use this height calculator for a baby or toddler?

The Khamis-Roche method (Method 1) does not work for children under age 4. However, you can use Method 2 (Mid-Parental Height Formula) for any age, including babies and toddlers. It only needs the mother's and father's heights to give an estimate.

Why does the calculator ask for both parents' heights?

Genetics play a big role in how tall a child will be. About 60% to 80% of adult height comes from genes passed down by both parents. By using both the mother's and father's heights, the calculator gets a better picture of the child's genetic height potential.

What if I only know one parent's height?

Both parents' heights are required for the calculator to work. If you only know one parent's height, you can use a reasonable estimate for the other. Keep in mind that an inaccurate parent height will make the prediction less reliable.

Does this calculator work for adults to predict their height?

No. This tool is designed to predict a child's future adult height. Most people stop growing between ages 16 and 20. If you are already an adult, your height is unlikely to change, and this calculator would not give useful results.

Why are the results different between Method 1 and Method 2?

Method 1 (Khamis-Roche) uses more data — the child's current height, weight, age, and both parents' heights. Method 2 only uses the parents' heights. More data usually means a more accurate prediction, so the two methods may give slightly different results. Method 1 is generally more reliable.

What does the prediction range mean?

The prediction range shows the likely window where the child's actual adult height will fall. For example, a range of 5′ 7″ to 5′ 11″ means the child will most likely end up somewhere between those two heights. Younger children have wider ranges because there is more time for growth to vary.

What does percentage of adult height reached mean?

This shows how much of the child's predicted adult height they have already reached. For example, if a 10-year-old boy is at 78%, it means he has grown about 78% of his expected final height and still has about 22% of growth left.

Do I need to enter bone age?

No, bone age is optional. It is only available if a doctor has taken a hand or wrist X-ray to measure skeletal maturity. If you leave it blank, the calculator will still give a prediction using the child's regular age. Adding bone age can make the result more accurate.

Can nutrition or exercise change my child's predicted height?

Yes. While genetics set the main blueprint, good nutrition, regular physical activity, and enough sleep help a child reach their full height potential. Poor nutrition or chronic illness can prevent a child from reaching the height their genes allow.

Is this calculator accurate for children going through puberty early or late?

Early or late puberty can affect accuracy. Children who hit puberty early may have a growth spurt sooner but stop growing earlier. Late bloomers may keep growing longer. If your child's puberty timing is unusual, the prediction may be less precise. A bone age measurement can help improve accuracy in these cases.

Can I switch between feet/inches and centimeters?

Yes. Each method section has US/Imperial and Metric tabs at the top. Click the tab you want, and the calculator will automatically convert your entered values. There is also a separate height unit converter at the bottom of the page.

What is mid-parental height?

Mid-parental height is the average of the mother's and father's heights. It serves as a simple genetic baseline. The mid-parental formula then adds 2.5 inches for boys or subtracts 2.5 inches for girls to account for the typical height difference between males and females.

Should I use my height with or without shoes?

Always use your height without shoes. Shoes can add 0.5 to 2 inches, which would throw off the prediction. For the most accurate result, measure all heights barefoot against a flat wall.

Why does the child's weight matter for height prediction?

In the Khamis-Roche method, weight helps fine-tune the prediction, especially for younger children. A child's weight reflects their overall body development and can give clues about growth patterns. The formula gives weight less importance as the child gets older.

What does the growth curve chart show?

The growth curve chart plots your child's projected height from their current age to age 18. It also shows the 50th percentile average for comparison. The shaded band represents the prediction range. This helps you see how your child's growth may compare to typical growth patterns over time.

Can this calculator predict height for adopted children when parent heights are unknown?

Without biological parents' heights, the predictions will be less accurate. You can still use Method 1 if you enter reasonable estimates for parent heights, but the result should be treated as a rough guess. A doctor using growth charts and bone age X-rays would give a better assessment in this situation.

Does this height calculator replace a doctor's evaluation?

No. This calculator gives a helpful estimate, but it is not a medical diagnosis. If you have concerns about your child's growth, talk to a pediatrician. A doctor can track growth over time, check for health issues, and order tests like a bone age X-ray for a more complete evaluation.