Baby Percentile Calculator
WHO growth curves for weight & length, birth to 5 years.
How percentile works
Your child's percentile compares their measurement to an international growth standard for healthy children.[1] A 60th-percentile weight means 60% of babies of the same age and sex weigh less. A value between the 3rd and 97th percentile sits inside the calculator's displayed reference band. It is not a diagnosis; the trend over time matters more than one number. If you are still expecting, our Due Date Calculator sets a baseline for the first measurement at birth.
When to ask your pediatrician
A single measurement below the 3rd or above the 97th percentile is not something this calculator can interpret by itself. If a number changes suddenly, save the result and bring it to your child's next visit. Sleep is the other main growth signal, see our Sleep Needs by Age guide.
Read more: Baby Percentile Explained: What the Number Actually Means.
Frequently asked questions
What does the 50th percentile mean?
A 50th-percentile weight means your baby weighs more than about half of babies the same age and sex, and less than the other half. Percentile is a ranking, not a grade. A value between the 3rd and 97th percentile sits inside the calculator's displayed reference band.[1] It is not a diagnosis, and babies do not need to be at or near the 50th percentile to be growing well.
Is a low percentile a problem?
Not by itself. A low percentile is one data point, not a diagnosis. Use the trend over time and your child's clinical context. If the number changes suddenly, or if feeding, illness, or symptoms have changed, bring the measurement to your pediatrician instead of interpreting it from the calculator alone.
What is the difference between WHO and CDC growth charts?
The WHO charts describe how healthy, breastfed children grow under ideal conditions, and CDC guidance uses them for infants and young children from birth to 2 years.[4] CDC then recommends transitioning to CDC Growth Charts at age 2. The switch is standard practice and does not mean your child's growth has changed.
Does my baby's percentile change over time?
Yes. Percentiles can change over time, especially when measurements are taken at different visits or with small differences in technique. The useful pattern is the trend, not one isolated result. If the curve changes suddenly or the measurement does not fit what you are seeing at home, bring it to your pediatrician.
Which measurement matters most?
This tool reports weight and length percentiles. Clinicians may also track head circumference and look at all measurements together rather than relying on one number.
How often should my baby be measured?
Your baby is usually measured at routine well-child visits, and more often if your pediatrician is tracking a feeding, illness, or growth concern. The exact schedule varies by country and clinician, so use your child's appointment plan as the reference.