Baby Weight-for-Length Percentile Calculator

Weight-for-length (WFL) measures how heavy a child is relative to their height, independent of age. It is the closest equivalent to BMI in children under 2 years. A baby at the 95th percentile for WFL is heavier relative to their length than 95% of babies of the same length — regardless of how old they are.

Because WFL directly compares a child's weight to other children of the exact same length. A tall 3-month-old and a short 9-month-old might have the same length — WFL shows whether each is appropriately proportioned for that length. Age-based charts (weight-for-age) answer a different question: 'How does this baby compare to other babies their age?'

Above the 97th percentile for WFL may indicate a child is gaining weight faster than expected for their length, sometimes called 'overweight for length.' In infants under 6 months who are exclusively breastfed, high WFL is usually not a concern. In formula-fed infants or toddlers, a consistently high WFL warrants discussion with your pediatrician.

Below the 3rd percentile for WFL may indicate 'wasting' — low weight relative to length. This can result from acute malnutrition, illness, or feeding difficulties. It is more urgent than low weight-for-age because it reflects current nutritional status rather than historical growth.

Both are useful but answer different questions. Weight-for-age tells you how your baby compares to other babies of the same age. Weight-for-length tells you if their weight is proportionate to their size (regardless of age). Pediatricians use both, along with length-for-age, to get a complete picture of growth.

The WHO weight-for-length table covers recumbent (lying-down) length from 45 to 110 cm. This corresponds roughly to birth through 24 months for most children. For standing heights above approximately 87 cm (typically 24+ months), the WHO uses the weight-for-height (standing) table instead.