Child Growth Percentile Calculator
Compare your child's height and weight against WHO or CDC growth standards to see where they fall among peers. Use this tool at pediatric check-ups or whenever you want to track growth trends over time.
About this calculator
Growth percentile charts compare a child's measurements to a reference population of the same age and sex. The calculator uses a z-score-style approach: it finds how far a child's height deviates from the expected mean for their age and gender, then converts that deviation into a percentile. The core formula is: Percentile ≈ 50 + ((height − expectedMean) / SD) × scaleFactor, where expectedMean and SD are derived from age- and gender-specific reference values, and scaleFactor differs between WHO (16.7) and CDC (15.3) standards. The 50th percentile represents the median child; the 85th and above may indicate overweight risk, while below the 5th may warrant clinical review. WHO standards are typically used for children under 2, while CDC charts apply from age 2 onward.
How to use
Suppose you have a 5-year-old boy (age = 5) who is 44 inches tall, using the CDC chart. Expected mean height = 30 + 5 × 2.5 = 42.5 inches. SD = 2.8 + 5 × 0.1 = 3.3. Z-score = (44 − 42.5) / 3.3 ≈ 0.455. Percentile = 50 + 0.455 × 15.3 ≈ 50 + 6.96 ≈ 57th percentile. This means the boy is taller than about 57% of boys his age according to CDC standards, which is solidly within the normal range.
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.