Child Growth Percentile Calculator
Compare your child's height with the CDC (ages 2–20) or WHO (birth to 5 years) growth references to see the height-for-age percentile for their sex. Use it at pediatric check-ups or whenever you want to track growth over time.
Last updated: September 2026
Formula below · 3 sources (CDC, aap.org, healthychildren.org) · Updated Sep 2026
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About this calculator
Growth percentile charts compare a child's measurement with a reference population of the same age and sex. This calculator converts height from inches to centimetres and uses the official reference values: for the CDC option, the CDC 2000 stature-for-age LMS tables (ages 2–20, interpolated to the exact age), with z = ((height ÷ M)^L − 1) ÷ (L × S); for the WHO option, the WHO 2006 Child Growth Standards for length-for-age (under 24 months, measured lying down) and height-for-age (24–60 months), with z = (height − M) ÷ (M × S). The z-score is then converted to a percentile with the normal distribution. The 50th percentile is the median child; the CDC flags heights below the 3rd percentile (or a fall across two major percentile lines) for short-stature evaluation. The CDC and AAP recommend the WHO standards from birth to 2 years and the CDC charts from age 2, so ages outside each chart's range return a message. Weight is not used: for weight status use the BMI-for-age percentile calculator.
How to use
Suppose you have a 5-year-old boy who is 44 inches tall and choose the CDC chart. Step 1: 44 in × 2.54 = 111.8 cm. Step 2: the CDC reference for boys at 5.0 years has a median of about 108.9 cm (L ≈ 1.26, S ≈ 0.043). Step 3: z = ((111.8 ÷ 108.9)^1.26 − 1) ÷ (1.26 × 0.043) ≈ 0.62. Step 4: convert to a percentile: about the 73rd percentile, so he is taller than about 73% of boys his age — solidly within the normal range. For a child under 2, choose the WHO option and enter the length measured lying down.
Frequently asked questions
What is the difference between WHO and CDC growth charts for children?
The WHO growth charts were developed using data from children in six countries raised under optimal conditions, including breastfeeding, making them a prescriptive standard for how children should grow. The CDC charts are based on a nationally representative U.S. sample and are descriptive of how American children actually grew. WHO charts are generally recommended for children under 2 years, while CDC charts are preferred for ages 2 and older. Your pediatrician will typically switch between these standards at the 2-year well-child visit.
What growth percentile range is considered healthy for a child?
Most pediatricians consider any percentile between the 5th and 95th to be within the normal range for a single measurement. More important than a single percentile is consistency over time — a child tracking steadily at the 20th percentile is generally healthy, while a child who drops from the 60th to the 15th percentile in a short period may warrant further evaluation. Percentiles above the 85th for weight-for-height may indicate overweight risk, and below the 5th may signal undernutrition or growth disorders. Always interpret results alongside a healthcare provider.
How often should I check my child's growth percentile?
Pediatricians typically measure growth at every well-child visit — monthly in the first year, then at 2, 4, 6, 9, 12, 15, 18, and 24 months, and annually from age 2 onward. Tracking at these intervals allows clinicians to spot trends such as growth faltering or rapid weight gain early. Parents can use this calculator between visits to stay informed, but a single measurement is less meaningful than the trajectory across multiple data points. If you notice a significant shift in percentile category, bring it to your pediatrician's attention.