Read the method
What a family height reference can tell you
Family height, a current percentile, and an individual future-height forecast answer different questions. This page calculates the first two transparently. It does not implement a validated individual prediction model or infer remaining growth from one measurement.
What the family-height result means
The result combines both parents' heights with a conventional 13 cm sex adjustment. It gives a family reference to compare with measured heights. A child may grow above or below it; the number is neither a height limit nor a personal forecast.
The mid-parental height formula
For boys: (father's height + mother's height + 13 cm) ÷ 2. For girls, subtract 13 cm instead. The adjustment reflects a historical population difference. It does not account for every family's ancestry, health or puberty timing.
For boys
(father + mother + 13 cm) ÷ 2
For girls
(father + mother − 13 cm) ÷ 2
Read the CDC curve and age table
The curve and table use official CDC 2000 stature-for-age LMS data, with medians interpolated at each whole year from ages 2 to 18. P50 is the median: half the reference population is shorter and half taller. It is not an arithmetic mean or a height every child should reach.
Explore the reference curve
Switch the reference group, move the age slider, and see the selected row highlighted in the table.
Reference height
138.6 cm
Age
| Age | Height |
|---|---|
| 86.5 cm | |
| 95.0 cm | |
| 102.2 cm | |
| 108.9 cm | |
| 115.4 cm | |
| 121.8 cm | |
| 127.9 cm | |
| 133.5 cm | |
| 138.6 cm | |
| 143.5 cm | |
| 149.1 cm | |
| 156.1 cm | |
| 163.8 cm | |
| 169.9 cm | |
| 173.5 cm | |
| 175.3 cm | |
| 176.2 cm |
CDC 2000 stature-for-age LMS data, interpolated at each exact age. P50 is the median, not the arithmetic mean. Table values are shown to one decimal; healthy children need not match this line.
Use each result for the question it answers
The parent formula gives a family reference. The CDC comparison places today's measurement among children of the same age and reference sex. Neither result tells you how much growing remains; that question needs an individual assessment and may require serial measurements and clinical information.
Parent formula
A family reference based only on parents’ heights and a sex adjustment. It does not calculate individual remaining growth.
Current CDC context
Age and current height place a measurement on the CDC reference distribution. The family value remains unchanged.
Repeated growth measurements
A series of dated values reveals change over time. For percentiles of height or weight, use the dedicated calculator.
Clinical assessment
A clinician can assess health, puberty, growth history and other factors when an individual evaluation is needed.
Which inputs affect which result?
Age and current height affect the CDC comparison, not the parent formula. Weight is not used in either calculation. To check height and weight percentiles together, open the separate percentile calculator.
How to measure height at home
Measure standing height consistently and record the date. Small differences in posture or technique can change the reading by a centimetre or more. A baby's recumbent length is a different measurement and needs a matching reference.
- 01
Use a hard floor
Measure barefoot on a level floor against a flat wall, with heels together and shoulders relaxed.
- 02
Keep the head level
Look straight ahead and place a flat book gently on top of the head. Do not stretch the neck or stand on tiptoe.
- 03
Repeat consistently
Measure at a similar time of day and record the date. Repeating the same process makes changes easier to interpret.
What can influence growth
Genes, health and development all influence height. Nutrition, sleep and activity support normal growth but do not guarantee a particular final height. Treat the family reference and population percentiles as context for understanding measurements.
Growth spurts and puberty timing
Children do not grow at a constant rate, and puberty starts at different times. One measurement cannot establish maturity or remaining growth. Keep dated records to see a pattern, and discuss sustained or unexpected changes with a healthcare professional.
When to ask a healthcare professional
Ask for individual advice about unexpected changes in growth, symptoms or puberty timing. Bring dated measurements and relevant family history. A single percentile cannot diagnose the cause of a growth pattern.
Height calculator vs. growth chart
The family formula summarizes parental height. A growth chart places a current measurement within an age- and sex-specific reference population. Neither by itself establishes a child’s future adult height.
| Factor | Height calculator | Growth chart |
|---|---|---|
| Purpose | Describe a family-based height reference | Track current height against peers |
| Data needed | Both parent heights and formula sex adjustment | Age and current height |
| Best for | Understanding the family formula | Monitoring change over time |
| Limitation | Cannot predict individual remaining growth | Not an adult-height prediction |
Growth spurts and puberty timing
Timing varies widely. These broad orientation points are not milestones every child must follow.
Typical pattern for boys
- Puberty often begins around 11–12
- Fastest growth is commonly around 13–15
- Growth usually slows around 16–17
Typical pattern for girls
- Puberty often begins around 9–10
- The main growth spurt is commonly around 10–14
- Many reach adult height around 15–16
What helps children reach their potential?
Genetics sets much of the expected range. Everyday health supports the body as it follows that range.
Balanced nutrition
Regular meals with protein, calcium, vitamin D, and zinc support normal bone and tissue development.
Consistent sleep
School-age children often need around 9–11 hours, while teenagers commonly need 8–10 hours.
Active play
Running, jumping, and sports support bone strength and overall development, even though no exercise can extend closed growth plates.
A formula result is not a personal forecast.
The parent formula cannot establish how many centimetres a particular child has left to grow. No confidence level, accuracy percentage, or individual prediction interval has been validated for this tool. Clinical assessment may consider repeated measurements, puberty and, when indicated, bone age.
Using the height calculator
Can this tell me exactly how tall my child will be?+
No. It provides a mid-parental family reference and a separate CDC comparison for a current measurement. It does not calculate an individual's final height or a validated prediction interval.
Can I use the family formula for a baby?+
You can calculate the parent formula without a child's current measurement, but it remains a family reference. CDC standing-height comparisons start at age 2. For a baby, use the WHO Baby Length Percentile Calculator with a recumbent measurement.
Is the median the same as the average?+
No. An arithmetic mean is the total divided by the number of observations; the median is the middle value, or P50. The CDC curve and table on this page show medians.
What if measured height is already above the family reference?+
That can happen: the family reference is not a ceiling. The measured height stays unchanged, and the formula value is shown separately rather than presented as a lower future height.
Does weight change this calculation?+
No. The family formula uses parents' heights and a sex adjustment. The CDC height comparison uses age, reference sex and current height. Use the percentile calculator for a separate weight-for-age comparison.
Is this a medical growth assessment?+
No. Growth assessment also considers measurement history, symptoms, family history and puberty. A healthcare professional can assess those factors together; this calculator provides reference values.
Can I compare the values in 3D?+
Yes. The comparison button beside the result can carry the current measurement, the labelled family reference and the parents' heights into one 3D scene.
Where do the growth values come from?+
They use official CDC 2000 stature-for-age LMS data, interpolated for age. The dataset represents a U.S. reference population, so it is not a universal growth target.
Further reading
The CDC median and percentile comparisons use official CDC 2000 LMS data. The parent formula is shown separately and is not an implementation of Khamis–Roche or a bone-age model.
- CDC 2000 stature-for-age LMS data (official statage.csv)
- CDC growth-chart interpretation guidance
- Mid-parental formula: conventional ±13 cm adjustment, shown without a prediction interval