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CDC Weight-for-Length Growth Chart (0-36 Months)

Plot your child's weight relative to their length using CDC reference data. This chart assesses whether a child's weight is proportionate to their body length, independent of age.

LMS Method: Z = ((X/M)^L - 1) / (L x S)

How It Works

This calculator uses CDC growth reference data to assess weight-for-length in children from birth to 36 months. Unlike weight-for-age, which compares weight to age, weight-for-length evaluates whether a child's weight is proportionate to their body size. This is particularly useful for identifying children who may be under- or overweight relative to their stature. The LMS method computes Z-scores using length-specific parameters.

Example Problem

A boy with a recumbent length of 65 cm weighs 7.93 kg. What is his weight-for-length percentile?

  1. Select 'Boy' for gender.
  2. Enter 65.0 cm for length.
  3. Enter 7.93 kg for weight.
  4. The calculator finds the LMS parameters for boys at 65 cm and computes the Z-score.
  5. Result: approximately the 50th percentile, as 7.93 kg is near the CDC median weight for boys at 65 cm.

Key Concepts

Weight-for-length assesses body proportionality independently of age. A tall child may be heavy for their age but perfectly proportionate for their length. Percentiles below the 3rd may suggest undernutrition, while above the 97th may suggest excess weight. This measurement is especially useful when a child's exact age is uncertain. For children over 2 years, weight-for-stature (standing height) is used instead.

Applications

  • Assessing body proportionality in infants and toddlers
  • Identifying wasting (low weight-for-length) in young children
  • Screening for overweight when weight-for-age alone may be misleading
  • Nutritional assessment in community health programs
  • Monitoring recovery from malnutrition

Common Mistakes

  • Confusing weight-for-length with weight-for-age — they measure different things
  • Using standing height instead of recumbent length for children under 2
  • Entering length in inches without converting — verify the unit selection
  • Using this chart for children whose length exceeds the chart range — switch to weight-for-stature (CDC 2-20)
  • Ignoring that a child at a high weight-for-length percentile may simply have a larger body frame

Frequently Asked Questions

How is weight-for-length different from weight-for-age?

Weight-for-age compares a child’s weight to other children of the same age. Weight-for-length compares weight to other children of the same body length, which better assesses whether the child’s weight is proportionate to their size.

What length range does this calculator cover?

This calculator covers lengths from 45 cm to 103.5 cm, which corresponds to the CDC reference range for infants and toddlers from birth to approximately 36 months.

Should I measure length or height?

For this chart, use recumbent length (measured lying down). Standing height is about 0.7 cm shorter than recumbent length. For children measured standing, use the CDC weight-for-stature chart instead.

Reference: CDC Growth Charts: United States. National Center for Health Statistics, 2000. https://www.cdc.gov/growthcharts/

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