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WHO Weight-for-Length Growth Chart (0-24 Months)

Plot your child's weight relative to their recumbent length using WHO growth standards. This chart assesses whether weight is proportionate to body size, independent of age.

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

How It Works

This calculator uses WHO growth standards to assess weight-for-length in children from birth to 24 months. Unlike weight-for-age, weight-for-length evaluates whether a child's weight is proportionate to their body size. This is particularly useful for identifying wasting (low weight-for-length) and overweight. The WHO data covers lengths from 45 cm to 110 cm using daily LMS parameters for precise calculations.

Example Problem

A boy with a recumbent length of 70 cm weighs 8.5 kg. What is his weight-for-length percentile?

  1. Select 'Boy' for gender.
  2. Enter 70.0 cm for length.
  3. Enter 8.5 kg for weight.
  4. The calculator finds the LMS parameters for boys at 70 cm and computes the Z-score.
  5. Result: approximately the 50th percentile, indicating the child's weight is proportionate to his length.

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. Below the 3rd percentile may suggest wasting (acute undernutrition). Above the 97th may suggest overweight. The WHO recommends weight-for-length for children under 2 (measured lying down) and weight-for-height or BMI-for-age for children 2 and older (measured standing).

Applications

  • Identifying wasting (acute undernutrition) in infants and toddlers
  • Screening for overweight when weight-for-age alone may be misleading
  • Nutritional assessment in community health programs
  • Monitoring recovery from acute malnutrition
  • Assessing body proportionality when exact age is uncertain

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
  • Using this chart for children whose length exceeds 110 cm — switch to weight-for-height
  • Not converting units properly — verify the unit selection matches your measurement
  • Ignoring that a child at a high 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. A tall child may be heavy for their age but perfectly proportionate for their length.

When should I use weight-for-length vs. BMI?

The WHO recommends weight-for-length for children under 2 years (measured lying down) and BMI-for-age for children aged 2 and older (measured standing). Weight-for-length is preferred for younger children because BMI can be less reliable at very young ages.

What length range does this calculator cover?

This calculator uses WHO data covering lengths from 45 cm to 110 cm, which spans roughly from birth through 24 months for most children. Lengths outside this range are not covered by the WHO weight-for-length growth standards.

Should I measure length or height?

For children under 2 years, use recumbent length (measured lying down). Standing height is typically about 0.7 cm shorter. If you only have standing height, you can add 0.7 cm to approximate recumbent length for this chart.

Reference: WHO Child Growth Standards. World Health Organization, 2006. https://www.who.int/tools/child-growth-standards

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