Baby percentile calculator
Enter one measurement to get its percentile and z-score on the WHO growth standards. It works for weight, length or height, and head circumference, from birth to 5 years and beyond for weight and height.
Your result
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Fill in the birth date, the date measured, and the measurement.
- Z-score
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- Age used
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Keep every measurement on one chart
TotBuddy plots each weight, length, and head measurement over time, and your partner sees the same chart on their phone.
How the calculator works
The calculator looks up the WHO LMS values for your child's age and sex, works out the z-score, and turns it into a percentile. These are the same tables and the same code that the TotBuddy app uses. A percentile says how many of 100 children of the same age and sex in the WHO reference group measure less than your child.
One measurement is a snapshot. To see how your child's line moves between visits, readhow TotBuddy's growth charts work.
Source: WHO Child Growth Standards.
This calculator gives information and does not provide medical advice. Follow your child's doctor's plan.
Percentile calculator questions
Which growth chart does this calculator use?
It uses the WHO Child Growth Standards from birth to 5 years and the WHO Growth Reference 2007 after that: weight to 10 years and height to 19 years. Head circumference is available from birth to 5 years.
Should I use corrected age for my premature baby?
For a baby born before 37 weeks, the calculator uses the corrected age until the second birthday when you enter the weeks at birth. Corrected age is the age from birth minus the weeks born early.
Why does the calculator ask how my child was measured?
The WHO tables measure babies lying down until age 2 and standing after that. Standing height is about 0.7 cm less than lying length, so the calculator adjusts a measurement taken the other way before it looks up the percentile.
Does the calculator store what I enter?
No. The calculation runs in your browser, and nothing you enter is sent to TotBuddy or anyone else.