Weight-for-Length Percentile Calculator

Enter your child's length (or height) and weight to see if their weight is proportional for their size. Uses CDC growth chart data for children from birth to age 5.

What is a weight-for-length percentile? A weight-for-length (or weight-for-stature) percentile shows whether your child's weight is proportional to their length or height, independent of age. It uses the LMS method with CDC Growth Chart data (2000). For infants measured lying down (45–103.5 cm), the chart is called "weight-for-length." For children measured standing (77–121.5 cm), it is called "weight-for-stature." This calculator automatically selects the correct chart. Learn more about how growth percentiles work.

This tool is for informational purposes only and is not a substitute for professional medical advice. Always consult your child's pediatrician.

How Weight-for-Length Percentiles Work

Weight-for-length percentiles evaluate whether your child's weight is appropriate for their body size, independent of age. This is different from weight-for-age, which compares weight to other children of the same age. Weight-for-length is especially useful for infants and young children because it can identify overweight or underweight status even when the child's exact age is uncertain.

The CDC provides two related datasets:

This calculator automatically selects the correct chart based on the measurement length and your chosen measurement type. When the length falls in the overlap range (77–103.5 cm), selecting "Auto" will use the recumbent (lying) chart by default.

When Is Weight-for-Length Used?

Pediatricians and nutritionists use weight-for-length percentiles to:

Unlike BMI-for-age (which is recommended starting at age 2), weight-for-length can be used from birth and does not require knowing the child's age.

Recumbent Length vs Standing Height

Children under 2 years are typically measured lying down (recumbent length), while children aged 2 and older are measured standing (stature). Recumbent length is generally about 0.7 cm longer than standing height for the same child, which is why the CDC provides separate reference charts. If a child under 2 is measured standing, the CDC recommends adding 0.7 cm before plotting on the recumbent chart.

Weight-for-Length FAQ

What is the difference between weight-for-length and weight-for-age?
Weight-for-age compares your child's weight to other children of the same age. Weight-for-length compares weight to children of the same body size (length or height), regardless of age. Weight-for-length is better for assessing whether a child's weight is proportional to their frame.
When should I use weight-for-length vs BMI-for-age?
Weight-for-length is used for children from birth to about age 5 (covering lengths 45–121.5 cm). BMI-for-age is recommended for children aged 2 to 20. For children between 2 and 5, both metrics can be used, but BMI-for-age is generally preferred for screening overweight and obesity in this age range.
What does it mean if my baby is above the 95th percentile for weight-for-length?
A weight-for-length above the 95th percentile means your child weighs more than 95% of children with the same body length. This may indicate excess weight relative to body size. However, a single reading is not diagnostic — your pediatrician will consider the trend over time, feeding patterns, and other factors before making any recommendations.
What is wasting, and how is it identified?
Wasting is a form of acute malnutrition identified when a child's weight-for-length z-score falls below −2 (approximately below the 2nd percentile). Severe wasting is defined as a z-score below −3. Wasting can result from illness, inadequate food intake, or both. It requires medical evaluation and nutritional intervention.
Why does the calculator use two different charts?
The CDC provides separate reference data for recumbent length (lying down, birth to 36 months) and standing stature (2 to 5 years) because recumbent length measures about 0.7 cm longer than standing height. Using the correct chart ensures accurate percentile calculations for how the child was actually measured.
Is weight-for-length available from the WHO?
Yes, the WHO provides weight-for-length and weight-for-height standards, but this calculator currently uses the CDC dataset only. The CDC weight-for-length and weight-for-stature charts are widely used in US pediatric practice.