Length-for-Age Percentile Calculator (WHO, 0-24 Months)

How Length-for-Age Percentiles Work

Length-for-age (or height-for-age for children measured standing) compares your child’s length to the lengths of other children of the same age and sex. The WHO growth standards are based on a study of healthy breastfed children from six countries around the world.

Children under 2 years are typically measured lying down (recumbent length). Standing height is generally about 0.7 cm shorter than recumbent length, so the measurement method matters for accuracy.

Understanding Length Percentiles

A percentile tells you what percentage of children are shorter than yours at the same age. For instance, a child at the 80th percentile is longer than 80% of children of that same age and sex.

• 3rd to 97th percentile is the normal range
• Below 3rd percentile may indicate short stature
• Above 97th percentile indicates tall stature
• Consistency along a percentile line is more important than the specific number

Example Calculation

A 12-month-old boy measuring 75.7 cm would be at approximately the 50th percentile, since the WHO median length for boys at 12 months is 75.75 cm.

Frequently Asked Questions

What is the difference between length and height?

Length is measured with the child lying down (recumbent) and is standard for children under 24 months. Height is measured standing up. Recumbent length is typically about 0.7 cm longer than standing height.

My child dropped percentiles. Should I be worried?

A shift of one percentile band is common and usually normal. Crossing two or more major percentile lines (for example, from the 75th to the 25th) warrants a conversation with your pediatrician to rule out nutritional or medical issues.

Do premature babies use the same chart?

For premature infants, pediatricians typically use corrected age (age from the due date, not birth date) until about 24 months. Enter the corrected dates to get a more appropriate comparison.

Are the WHO standards the same as CDC growth charts?

No. The CDC recommends using WHO growth standards for children under 2 years and CDC growth charts for ages 2-20. The WHO standards are based on how healthy breastfed children should grow, while CDC charts describe how children in the US actually grew during a specific time period.