40th percentile
At the 40th weight percentile, about 40 out of 100 babies of the same age and sex on the chart weigh less.
Not your baby's result.
Baby Percentile Calculator
What do your baby's growth percentiles mean?
Check weight, length, or head size with WHO growth charts. See what the number means in simple words.
WHO chartsFree to useNo account
For babies under 2 born at 37 weeks or later.
Example only40th percentileNot your baby's result.
Baby Percentile Calculator
Find your baby's growth percentiles.
Enter a measurement and see how it compares on a WHO chart. For babies under 2 born at 37 weeks or later.
About your baby
These details help us use the right chart.
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Let's check a few details
WHO growth standardsBased on World Health Organization charts.
Age on measurement dateWe use your baby's age on the date you enter.
Private in your browserYour entries are not sent to our server.
Understanding percentiles
A percentile is a
comparison, not a grade.
One measurement is part of your baby's bigger growth story.
A percentile shows how a measurement compares with babies of the same age and sex on the growth chart.
A higher percentile does not automatically mean better health. Your pediatrician can look at growth over time and your baby's overall health.
Read the guideHow it works
Three simple steps. More clarity.
Use a recent measurement and read the number in context.
- 01
Enter a measurement
Add the dates and at least one measurement.
- 02
See the percentile
View each measurement on a WHO chart.
- 03
Read the context
Learn what the number can and cannot tell you.
Growth guides
Helpful answers for growing families.
Clear words for the questions parents ask.
Does a percentile tell me if my baby is healthy?
A percentile alone cannot tell you that. Your pediatrician looks at growth over time and your baby's overall health. This tool provides information, not a diagnosis.
Do I need all three measurements?
No. You can check weight, length, or head circumference on its own. Enter at least one measurement and leave the others blank. If you enter more than one, use measurements taken on the same date. Read measurement tips.
What if my baby's percentile changes?
One number cannot explain a change. Measurement technique, age, and the chart used all matter. Your pediatrician can look at measurements over time and your baby's overall health.
Can I use this for a premature baby?
This version is for babies born at 37 weeks or later. If your baby was born earlier, or you're not sure, ask your pediatrician which chart and age to use.
Our approach
Clear about how the numbers work.
Simple to use. Honest about its limits.
WHO growth standards
Used here for babies under 2 born at 37 weeks or later.
Age on the measurement date
Calculated in days from your baby's birth date.
Private in your browser
No account needed. Your entries are not sent to a server.
We use the WHO growth standards for children younger than 2 and follow CDC guidance on growth charts.
For information, not a diagnosis.
A little more clarity
Wondering what a measurement means?
Check a percentile, then read the result in simple words.
Use the calculatorFreeNo accountBabies under 2
For babies born at 37 weeks or later.
