Weight-for-age
Weight compared with babies of the same sex and age.
Percentile
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Z-score
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Weight-for-age: result not available yet.
Enter the measurements and calculate to see this result.
WHO growth chart calculator
Baby Growth Percentile Calculator
Calculate WHO percentiles for weight, recumbent length, head circumference, and weight-for-length from birth through 24 months. The math runs in your browser using bundled CDC/WHO LMS data.
- Charts
- WHO 0-24 mo
- Outputs
- 4 indicators
- Data
- Bundled JSON
Results
Four WHO percentiles.
Percentiles are rounded for display. Z-scores show the same LMS result on the standard-deviation scale.
Length-for-age
Recumbent length compared with babies of the same sex and age.
Percentile
—
Z-score
—
Length-for-age: result not available yet.
Enter the measurements and calculate to see this result.
Head circumference-for-age
Head circumference compared with babies of the same sex and age.
Percentile
—
Z-score
—
Head circumference-for-age: result not available yet.
Enter the measurements and calculate to see this result.
Weight-for-length
Weight compared with babies of the same sex and recumbent length.
Percentile
—
Z-score
—
Weight-for-length: result not available yet.
Enter the measurements and calculate to see this result.
The method
WHO LMS math, visible.
- 01
Convert measurements to metric.
Weight is converted to kilograms, and length plus head circumference are converted to centimeters before the LMS lookup.
- 02
Interpolate the matching WHO row.
Age-based indicators use age in months from UTC-safe day math. Weight-for-length uses recumbent length in centimeters.
- 03
Convert LMS z-score to percentile.
The calculator uses the CDC LMS formula and a local Gaussian CDF. No CDC or WHO runtime request is made.
Trust & methodology
A growth tool with a paper trail
The data is bundled from official CDC WHO Growth Charts files, and the page keeps chart boundaries visible for parents and caregivers.
Last sitewide review
April 21, 2026
Maintained by
Baby Milk Calculator editorial team
Editorial policy
Who writes the site, how sources are chosen, how updates and corrections are handled.
Read
How we calculate
The intake ranges, unit conversions, and guardrails behind every result.
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Corrections & contact
Send a question or correction to support@milkcalculator.org.
Read
SourcesAmerican Academy of PediatricsCenters for Disease Control and PreventionWorld Health Organization
Growth chart guide
Read the result carefully.
01
What is a baby growth percentile?
A percentile places one measurement on a reference curve. For example, a weight-for-age percentile compares a baby's weight with babies of the same sex and age in the WHO reference. One measurement is a snapshot; growth over time is the more useful pattern to review with a pediatrician.
02
Which growth charts does this use?
This calculator uses the WHO Child Growth Standards for birth through 24 months, using the CDC-hosted LMS data files for weight-for-age, length-for-age, head circumference-for-age, and weight-for-length.
03
Why recumbent length?
Under age 2, the expected measurement is recumbent length: the baby is measured lying down. CDC training notes that switching from recumbent length to a standing measurement can shift chart interpretation, so this page uses length throughout.
04
Why no BMI under 2 years?
CDC growth-chart training states that BMI-for-age is not recommended for children younger than 2 years. Weight-for-length is the included size comparison for this age range.
05
When to talk to a pediatrician
Ask your pediatrician about measurements that are hard to take, sudden percentile shifts, feeding concerns, low diaper output, or a result that does not match what you are seeing at home. If your baby seems very ill, dehydrated, hard to wake, or has trouble breathing, seek urgent medical care.
Related calculators
Pair growth with feeding context.
FAQ
Common questions.
01Which growth charts does this calculator use?
It uses WHO Child Growth Standards LMS values published through the CDC's WHO Growth Charts data files for babies from birth through 24 months.
02Why does it say recumbent length?
For children younger than 2 years, CDC guidance uses recumbent length measured lying down. Keep the same measurement method when comparing results over time.
03Why does this calculator skip BMI-for-age?
CDC growth-chart training notes that BMI-for-age is not recommended for children younger than 2 years, so this calculator uses weight-for-length instead.
04Can I use this for a premature baby?
Use it as a discussion aid only. Premature babies may need corrected-age tracking or an individualized growth plan from their pediatrician or NICU team.
05Do percentiles decide a growth concern?
No. Percentiles are tracking points. A pediatrician looks at measurement accuracy, trend over time, feeding history, medical history, and the full clinical picture.
References
Where the growth data comes from.
- WHO Growth Charts Data Files
CDC / National Center for Health Statistics
CDC-hosted WHO LMS data files for weight-for-age, length-for-age, head circumference-for-age, and weight-for-length charts.
- Using WHO Growth Standard Charts
CDC Growth Chart Training
CDC guidance on using WHO growth standards for U.S. children from birth to 2 years.
- WHO Child Growth Standards
World Health Organization
WHO documentation and standards for child growth indicators, including length, weight, and head circumference.
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