Height Calculator with WHO/CDC Growth Percentiles

Use the Height Calculator

Enter age, sex, and standing height to see an estimated height percentile and z‑score using WHO/CDC‑style references.

How to Use Height Calculator with WHO/CDC Growth Percentiles

1. Step 1: Select sex and age

   Choose Boy or Girl, then set age in years (2–20). Use the slider for fine control.

2. Step 2: Pick units

   Use Metric (cm) or US (ft/in). The input adapts to your choice.

3. Step 3: Enter height

   Measure without shoes on a hard floor. Enter the child’s standing height.

4. Step 4: Read the percentile

   See the estimated percentile, z‑score, and where the result falls on the curve.

5. Step 5: Compare to references

   Use the small table to compare typical 5th, 50th, and 95th percentiles for the selected age and sex.

Key Features

• WHO/CDC references
• Age/sex percentiles
• Table + visual bar
• Z‑score with context
• Mobile‑friendly inputs

Understanding Results

Height calculator tips

Measure barefoot on a hard floor, back to a wall, eyes level. Use a flat object at the crown and mark the wall to avoid reading the tape on an angle. Try to measure at roughly the same time of day; people are slightly taller in the morning.

Formula

The height calculator estimates a child’s percentile by converting the difference between the child’s height and the age‑specific median into a z‑score. In simple terms: we find the median (typical) height for a child of the same age and sex, estimate the expected spread of heights around that median, and express your child’s value relative to the group. The z‑score is then mapped to a percentile using the standard normal distribution (0 ↔ 50th percentile; ±1.645 ↔ 5th/95th percentiles).

Reference Ranges & Interpretation

As a rule of thumb, values between roughly the 5th and 95th percentiles are common in healthy populations. Children often track along a similar percentile band year to year. Clinicians pay attention to very low or very high values (below ~3rd, above ~97th) and to large, sustained changes in trajectory. In practice, the correct reference also depends on age: the WHO Child Growth Standardsare commonly used for birth–24 months (length), while the CDC growth chartsare often used for U.S. children 2–20 years (height).

Assumptions & Limitations

This tool is designed for education. It uses age‑specific medians and a typical spread to estimate percentiles and does not diagnose medical conditions. Measurement quality matters: measure barefoot, against a wall, and repeat for consistency. Always interpret results with a qualified professional who can consider family pattern, nutrition, puberty timing, and overall health.

Complete Guide: Height Calculator with WHO/CDC Growth Percentiles

Use our height calculator to see your child’s percentile by age and sex (WHO/CDC). Enter height and age to view a clear chart and a quick reference table.

What the height calculator shows

This height calculator translates a single measurement into an estimated percentile and z‑score for age and sex, using widely referenced growth curves. The percentile shows where a child sits among peers right now; the z‑score expresses the same idea on a statistical scale that makes changes easier to compare across ages. Used together over time, they form a clear trend line you can discuss with your pediatrician.

Results are most helpful when measurements are consistent: no shoes, heels to the wall, eyes forward, and a flat object to mark the top of the head. Taking two readings and averaging them reduces noise. If you also track weight and head circumference with our related tools, you’ll have a well‑rounded snapshot of growth to bring to your next visit.

What is a height percentile?

A height percentile compares one child's measurement to a large, age‑ and sex‑matched reference group. If your child is at the 75th percentile for height, they are taller than roughly 75 out of 100 children of the same age and sex in that reference. Percentiles do not grade health or predict the future by themselves; they simply show where a measurement falls within a population at one point in time.

Clinicians monitor trends over many visits because growth follows a pattern. Many children track along a similar percentile band as they age. Occasional shifts happen (for example, during a growth spurt), but large, sustained jumps or drops merit a closer look with your pediatrician.

How the height calculator works

The height calculator estimates a child's height percentile by comparing their height to age‑specific reference curves for boys and girls. To keep the tool fast and mobile‑friendly, it uses an established z‑score approach: it matches your child's age and sex to an age‑specific median and spread (the expected variability around that median), then converts the difference into a z‑score. That z‑score maps directly to a percentile using the standard normal distribution. Results are rounded to one decimal place for clarity.

Although the WHO Child Growth Standards are preferred for children under 2 years (measured lying down as length) and the CDC growth charts are often used for U.S. children 2–20 years (standing height), the principle is the same: match age and sex, reference the appropriate curve, compute a z‑score, and read the corresponding percentile. In our app, we present a concise reference table (5th to 95th percentiles) and a simple bar to visualize where your child sits on the curve.

WHO vs CDC: which standard to use

The WHO Child Growth Standardsare based on an international cohort of healthy, breastfed infants and young children raised in ideal conditions, and are generally recommended from birth to 24 months. The CDC growth chartsdescribe how U.S. children 2–20 years grew during the survey years used to build the charts.

If your child is under 2 years, consider a length‑for‑age tool that aligns with WHO standards, such as our Baby Length Percentile Calculator. For 2–20 years, standing height percentiles (like this calculator) are appropriate in most U.S. contexts. Either way, results should be interpreted in the child's clinical context.

How to measure height correctly at home

Good measurements make percentiles meaningful. Measure height barefoot on a hard, level surface. Have the child stand straight with heels together and touching the wall, legs straight, shoulders relaxed, and looking forward with the head in the Frankfort plane (an imaginary line from the bottom of the eye socket to the ear canal). Use a flat object like a hardcover book against the top of the head and mark the wall; then measure that mark down to the floor with a tape measure. Avoid carpet and soft shoes. Repeat twice and average if needed.

Try to measure at a similar time of day. Height can vary slightly between morning and evening due to normal spinal compression. When you record several measurements over months, you'll see a smoother growth trend—exactly what clinicians look for.

Interpreting percentiles and z‑scores

The percentile tells you how your child compares with peers of the same age and sex. A 50th percentile is the median. A 10th percentile means shorter than 90% of peers; a 90th percentile means taller than 90% of peers. A z‑score expresses that same position on a standard normal curve: 0 is average, +1 is about the 84th percentile, −1 is about the 16th, and ±1.645 corresponds to the 5th and 95th percentiles.

In pediatrics, clinicians pay attention to values outside roughly the 3rd–97th percentile range, as well as patterns such as crossing two major percentile lines on a chart. But a single number rarely tells the whole story. Family patterns, puberty timing, nutrition, chronic illnesses, and medications all influence growth. Percentiles are one data point in a larger picture.

What percentile is normal?

Normal growth spans a wide range. Most healthy children fall between the 5th and 95th percentiles, and many track consistently near the same band year after year. Being at the 10th percentile is not "worse" than being at the 80th—it simply reflects genetics and biology. Clinicians are most concerned when a child falls very low (below ~3rd) or very high (above ~97th), or changes trajectory quickly.

For weight‑related questions, consider pairings like our Child BMI Percentile Calculatoror Waist‑to‑Height Ratio Calculator. Looking across these measures can clarify whether height and weight are in a healthy relationship for age.

What affects a child's height?

Height is strongly influenced by genetics. Most children grow to a stature consistent with their family pattern. Nutrition, sleep, physical activity, and general health also matter. Chronic illnesses, endocrine conditions (such as thyroid or growth hormone disorders), certain medications, and psychosocial stress can slow growth. Conversely, earlier puberty can temporarily make a child look tall for their age.

Pediatricians sometimes estimate a child's adult height using mid‑parental height formulas and bone age assessments. Our Growth Calculator and Growth Chart Calculatorcan help you explore trends over time. Use these tools as guides rather than promises; biology often defies simple predictions.

When to talk to a pediatrician

Reach out to your clinician if your child is below roughly the 3rd percentile, above the 97th percentile, or if you notice a clear change in growth trajectory—especially if there are symptoms like fatigue, headaches, delayed puberty, or significant weight changes. Early evaluation can identify nutritional issues or medical conditions that benefit from treatment.

Keep notes of measurements, diet, sleep, and activity. Bringing organized data to the visit helps your clinician see the full picture. Our Age Calculator can help you record exact ages on measurement dates, which improves accuracy when plotting growth.

Assumptions and limitations

This height calculator provides educational estimates using age‑ and sex‑specific medians and an assumed spread based on typical variability. It does not diagnose conditions or replace a professional growth assessment. For children under 2 years, recumbent length and WHO standards are preferred; for 2–20 years, standing height percentiles and CDC curves are common in U.S. practice. Ethnicity, secular trends, and sampling frames can shift where populations sit relative to these curves.

Measurements with shoes, on carpet, or with poor posture will skew results. Always interpret percentiles in clinical context with a qualified professional. If needed, your pediatrician may order a bone age X‑ray, lab tests, or refer to a pediatric endocrinologist.

For home tracking, aim for the same tape/wall, the same stance, and similar timing (for example, evenings after school). Small procedural tweaks reduce noise and make the trend trustworthy—exactly what you and your clinician need to make sense of changes between visits.

Related tools

• For infants under 2 years: Baby Length Percentile Calculator
• Weight context for age: Child BMI Percentile Calculator
• Head size for age: Head Circumference Percentile Calculator
• Visualize trends: Growth Chart Calculator
• Body proportions: Waist‑to‑Height Ratio Calculator

Frequently Asked Questions