WHO REFERENCE · 45–110 CM
Baby weight-for-length percentile calculator
Weight-for-length compares an infant’s weight with the WHO reference for infants of the same lying-down length and sex. It adds body-proportion context that weight-for-age cannot provide by itself.
Calculate weight-for-length ↗WORKED EXAMPLE
7.3 kg and 65.7 cm
For a girl weighing 7.3 kg with a recumbent length of 65.7 cm, the WHO weight-for-length result is about the 53.6th percentile. This is a reference position, not a diagnosis or a target.
Measure before you calculate
- Weigh the baby on a stable infant scale with clothing kept light and consistent.
- Measure recumbent length from the top of the head to the heel using a length board when possible.
- Repeat a surprising measurement and enter the matching weight and length from the same date.
Which comparison answers your question?
| Measure | Question answered | Main limitation |
|---|---|---|
| Weight-for-age | How does weight compare at this age? | Does not account for length. |
| Length-for-age | How does length compare at this age? | Does not account for weight. |
| Weight-for-length | How does weight compare at this length? | Does not interpret health or growth over time. |
How the calculation works
The calculator selects the WHO LMS parameters at the entered 0.1 cm length and converts the measurement to a percentile. Values between table rows are interpolated; values outside 45–110 cm are not estimated.
Questions parents ask
How is weight-for-length different from weight-for-age?
Weight-for-age compares weight with children of the same age and sex. Weight-for-length compares weight with infants of the same recumbent length and sex, so it answers a different question.
Does weight-for-length require age?
The WHO weight-for-length reference is indexed by recumbent length and sex. The main calculator still asks for dates so it can show the rest of the age-based growth snapshot.
What length range is supported?
This calculator uses the WHO weight-for-length table from 45.0 to 110.0 cm. It does not extrapolate outside that published range.
Can I use corrected age for a premature baby?
No. The site does not calculate corrected age or provide a preterm growth assessment. Ask the child’s healthcare professional which chart and age basis to use.
Source: WHO weight-for-length standards. See the calculation methodology and limits.
Review status: Maintained by Baby Growth and technically reviewed on 29 September 2026. Calculations and product ranges are checked against the cited WHO, CDC and manufacturer sources. This independent tool has not received clinical review and does not replace professional care.