What is a weight percentile?

A weight percentile compares a child’s weight with the CDC reference population of the same sex and age.

How is child weight percentile calculated?

The calculator selects the published CDC weight-for-age LMS row for the child’s sex and completed calendar month, converts weight to a z-score, and maps that z-score to a percentile.

What growth chart is used?

This page uses the CDC 2000 weight-for-age reference for children ages 2–20. It does not use WHO infant standards.

Is percentile a diagnosis?

No. A percentile is a reference comparison, not a diagnosis or treatment recommendation. Growth is best interpreted across accurate measurements over time with clinical context.

Child Growth Lab

Weight Percentile Calculator

Calculate child weight percentile using CDC growth standards for ages 2–20.

Pediatric growth calculators based on CDC and WHO growth standards.

Plain-language interpretation

Weight-for-age percentile compares a child’s weight with children of the same sex and age in the CDC reference population. It does not account for height or body proportions, and a single percentile does not determine health.

Methodology and data standard

The calculator uses published CDC 2000 weight-for-age L, M, and S parameters. Weight is converted to kilograms, mapped to the published CDC Agemos row, converted to a z-score with the LMS equation, and then converted to a percentile. L, M, and S coefficients are not interpolated.

Applicable age range

Ages 2–20, from the second birthday through the 20th birthday. This page does not calculate infant or WHO weight percentiles.

Worked example

A girl aged about 60.5 months who weighs 20 kg maps to the published CDC female weight-for-age row at Agemos 60.5. The LMS calculation gives a percentile near the 75th for that reference group.

Limitations

Weight-for-age does not account for height or body composition.
A single result does not assess growth velocity or a longitudinal trend.
Not for children younger than 2 years or infant growth standards.
Reference calculation only—not a diagnosis.

References

FAQ

What is a weight percentile?: A weight percentile compares a child’s weight with the CDC reference population of the same sex and age.
How is child weight percentile calculated?: The calculator selects the published CDC weight-for-age LMS row for the child’s sex and completed calendar month, converts weight to a z-score, and maps that z-score to a percentile.
What growth chart is used?: This page uses the CDC 2000 weight-for-age reference for children ages 2–20. It does not use WHO infant standards.
Is percentile a diagnosis?: No. A percentile is a reference comparison, not a diagnosis or treatment recommendation. Growth is best interpreted across accurate measurements over time with clinical context.

Content maintenance date: 2026-07-16. Editorial and methodology review: see Editorial and methodology review.