Calculate your child's weight, height, and BMI percentiles using WHO and CDC growth charts. Track growth from birth to age 20 with age and sex-matched comparisons.
Growth percentiles are the primary tool pediatricians use to monitor your child's physical development. By comparing your child's weight, height, and BMI to thousands of age and sex-matched peers, percentiles reveal whether growth is on a healthy trajectory.
For ages 0–2, the WHO growth standards (2006) are recommended internationally, reflecting how children should grow under optimal conditions. For ages 2–20, the CDC growth charts (2000) are the U.S. standard. This calculator uses the appropriate reference for your child's age.
Tracking three metrics together — weight-for-age, height-for-age, and BMI-for-age — gives a more complete picture than any single number. A child who is short and light (both at the 20th percentile) is proportionate; a child who is average height but very heavy may need nutritional guidance. Whether you are a beginner or experienced professional, this free online tool provides instant, reliable results without manual computation. By automating the calculation, you save time and reduce the risk of costly errors in your planning and decision-making process.
Between well-child visits, this calculator lets you monitor growth using the same reference data your pediatrician uses. Tracking weight, height, and BMI together gives a complete picture of your child's development. Having a precise figure at your fingertips empowers better planning and more confident decisions. Manual calculations are error-prone and time-consuming; this tool delivers verified results in seconds so you can focus on strategy.
BMI = weight(kg) / height(m)² Percentile calculation uses the LMS method: z-score = ((measurement / M)^L − 1) / (L × S) where L = power, M = median, S = coefficient of variation Percentile = Φ(z) × 100 (standard normal CDF) Weight-for-age: WHO 0–2 yr, CDC 2–20 yr Height-for-age: WHO 0–2 yr, CDC 2–20 yr BMI-for-age: WHO 0–2 yr (weight-for-length), CDC 2–20 yr
Result: Weight: 55th | Height: 42nd | BMI: 57th percentile
An 8-year-4-month-old girl weighing 58 lbs and measuring 50 inches falls at the 55th percentile for weight (average), 42nd for height (average, slightly below midline), and 57th for BMI (healthy weight). All three metrics are within the normal range (5th–85th) and proportionate to each other, indicating healthy, balanced growth.
Weight-for-age alone can be misleading — a tall child will naturally weigh more. Height-for-age alone misses nutritional status. BMI-for-age combines both but can't distinguish muscle from fat. By tracking all three together, you get the most complete picture of your child's growth. A child at the 80th percentile for weight, 80th for height, and 50th for BMI is proportionally large — perfectly healthy.
While percentiles show where your child is relative to peers, growth velocity shows how fast they're growing. Normal growth velocity varies by age: infants gain 5–7 inches/year, toddlers 3–5 inches/year, school-age children 2–3 inches/year, and puberty brings another 3–4 inches/year. Abnormally slow growth velocity warrants investigation even if the current percentile appears "normal."
Bring growth concerns to your pediatrician if: your child crosses two major percentile lines in either direction, BMI is above the 95th or below the 5th percentile, growth appears to have stalled (no height increase in 6+ months outside of puberty pauses), or there's a significant discrepancy between height and weight percentiles (e.g., 90th weight, 20th height).
For children ages 2–20, CDC categories are: Underweight = below 5th percentile, Healthy weight = 5th to 84th percentile, Overweight = 85th to 94th percentile, Obese = 95th percentile and above. Note that these categories are different from adult BMI categories, which use fixed BMI cutoffs rather than percentiles.
Not necessarily. A child who has always tracked near the 10th percentile is simply smaller than average, which is perfectly normal. Concern arises if a child's percentile drops significantly (e.g., from 50th to 10th over 6–12 months), which could indicate a growth or nutritional issue. Genetics play a major role — smaller parents tend to have smaller children.
The WHO growth standards are recommended for children 0–2 years (based on breastfed babies, representing how children should grow). The CDC growth charts are used for ages 2–20 years in the U.S. (representing how children did grow). Some practitioners use WHO charts through age 5. The key difference: WHO charts show slightly higher growth in the first months and lower from 3–12 months compared to CDC.
Puberty causes major shifts: early developers may temporarily jump to higher height percentiles, while late developers may appear to fall behind. Girls typically begin puberty at ages 8–13 and reach adult height by 14–16. Boys begin at 9–14 and may grow until 16–18. These timing differences can cause significant temporary percentile changes that normalize by adulthood.
A BMI above the 95th percentile meets the clinical definition of childhood obesity. However, this doesn't mean your child needs to "diet" — children are growing, so the goal is usually to slow weight gain while height catches up, rather than active weight loss. Focus on increasing fruits, vegetables, whole grains, and physical activity. Consult your pediatrician for a personalized plan.
At-home measurements can vary by 0.5–1 inch, which significantly affects percentile accuracy, especially for shorter children. For best results: measure in the morning (children are taller), use a flat wall and hard floor, ensure heels/buttocks/shoulder blades touch the wall, use a flat object on the head to mark the spot, and measure three times, using the average.