Baby Growth Percentile Calculator (WHO Weight, Length, Head)

Free baby growth percentile calculator using the WHO Child Growth Standards: enter age, weight, length and head circumference to see the percentile and z-score on the growth chart, corrected age for premature babies, and a private growth log that shows your baby's trend.

🔒 Private: nothing is uploaded. Your baby's details and growth log stay in this browser.

Baby is a

How old?

Date of birth

Measured on

Born early by

weeks

Measurements (any one is enough; type in either unit)

Weight

kgorlboz

Length / height

cmorin

Head circumference

cmorin

Enter a measurement and the percentile appears here.

Percentiles use the WHO Child Growth Standards (2006), built from healthy, breastfed babies in six countries, for ages 0 to 5. A percentile is not a grade: a healthy baby can be on any line between the 3rd and 97th. What matters is that growth follows its own curve. This is not medical advice; talk to your doctor or health visitor about any worry.

Baby growth percentile calculator

Enter your baby's sex, age and weight, length and head circumference to see which percentile each falls on, how that compares with the usual range for that age, and where it sits on the WHO growth chart. Save each doctor's visit to a private growth log to see the trend and whether your baby is following a steady curve.

Reading the result

50th percentile means half of babies of that age and sex are smaller and half are larger. 15th–85th is the middle of the range and 3rd–97th is the usual range.
A baby on the 10th percentile is not “behind”. Many healthy babies are small or large and stay there.
The trend matters more than one number. Falling across two or more of the main lines between visits is worth discussing with your doctor.

Questions

Do I use the WHO or CDC chart?

The WHO standards are used for children under 2 almost everywhere, including by the CDC and in Canada, the UK and Australia. They describe how healthy, mostly breastfed babies grow.

My baby was born early. Which age do I use?

Enter how many weeks early. Until age 2 the calculator uses the corrected age (from the due date), which is how premature babies are usually assessed. Very premature babies are often followed on special charts, so ask your neonatal team.

What is the birth weight percentile?

Enter age 0 days (or the birth date as the measured date) and the birth weight. This uses WHO standards for term babies; for birth weight by gestational age, doctors use charts such as Fenton or INTERGROWTH.

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