Baby Growth Percentile Calculator
Calculate your baby's weight-for-age, length-for-age, and head circumference percentiles based on official World Health Organisation (WHO) child growth standards.
Child Growth Measurements
WHO Percentile Results
⚖️ Decision Verdict: Healthy Proportionate Growth
Both weight (54th percentile) and length (50th percentile) track closely along the WHO median curve. Healthy infants vary widely across the 3rd to 97th percentiles; maintaining a steady individual growth channel is the most important clinical indicator.
Clinical Growth Parameters (WHO Standards)
About this tool
How to use it
- Select your baby's biological sex (Boy or Girl) and current age in months (0 to 24 months).
- Enter your child's most recent weight, length/height, and optional head circumference measurement.
- Toggle between Metric (kg, cm) and Imperial (lbs, inches) units as preferred.
- Click 'Calculate Percentiles' to view where your baby falls along the official WHO Child Growth Standards.
- Inspect the visual percentile spectrum bars (3rd, 15th, 50th, 85th, 97th percentiles) and clinical Z-scores.
Why it matters
The World Health Organization (WHO) Child Growth Standards are established from the Multicentre Growth Reference Study (MGRS), tracking healthy, breastfed infants raised in optimal socioeconomic and nutritional conditions across six diverse countries. Growth percentiles allow healthcare providers and parents to observe whether a baby's physical development is progressing consistently along their personal developmental curve.
When to use it
Use this tool following routine well-child pediatrician visits, health visitor checks, or monthly weigh-ins to log and understand growth curve percentiles.
Good to know
Informational Use Only: This calculator is designed purely for informational educational reference and does not provide medical diagnosis. A baby on the 10th percentile can be just as healthy as a baby on the 90th percentile; personal curve consistency is what pediatricians monitor.
Common questions
What does a growth percentile mean?
A percentile indicates how your baby's measurement compares to a representative group of 100 healthy babies of the same sex and age. For example, if your baby is in the 60th percentile for weight, they weigh more than 60 babies and less than 40 babies in that reference cohort.
Is the 50th percentile the 'best' percentile?
No. The 50th percentile simply represents the statistical median (average). Just like healthy adult heights vary, healthy infants normally range anywhere from the 3rd to 97th percentiles.
What is the difference between WHO and CDC growth charts?
WHO charts describe how healthy children *should* grow under optimal conditions (primarily breastfed cohorts). CDC charts reflect how US children actually grew in the 1970s–1990s (including formula-fed cohorts). The American Academy of Pediatrics (AAP) and UK NHS recommend WHO charts for all infants 0–24 months.
What is a Z-score in infant growth?
A Z-score indicates how many standard deviations a measurement is from the WHO median. A Z-score of 0 is exactly the 50th percentile. Scores between -2 and +2 standard deviations represent the normal 95% range.
When should I consult a pediatrician?
Consult your doctor if your baby crosses two or more major percentile lines suddenly (e.g. dropping from 75th to 25th), drops below the 3rd percentile, or displays feeding difficulties and lethargy.