Donaldson R F Child Growth Percentile Calculator
Compare a child's weight and height (or length) with official growth standards for their age and sex — from birth to 20 years.
Fill in one or both measurements. Under 2 years the length is measured lying down; from 2 years, standing height.
How it works
Growth charts use the LMS method: for each age and sex, three numbers (L for skewness, M for the median, S for variation) describe how a measurement is distributed. Your child's value is converted to a z-score, z = ((value ÷ M)L − 1) ÷ (L × S), and then to a percentile. A percentile of 60 means the child is bigger than about 60% of children of the same age and sex. The “typical range” shown is the 3rd to 97th percentile.
Data sources
Birth to 24 months: WHO Child Growth Standards — weight-for-age and length-for-age (WHO Multicentre Growth Reference Study Group, 2006), who.int/tools/child-growth-standards. 2 to 20 years: CDC Growth Charts for the United States — weight-for-age and stature-for-age (Kuczmarski RJ et al., Vital and Health Statistics Series 11, No. 246, 2002), cdc.gov/growthcharts. The CDC recommends the WHO standards for children under 2, which is what this tool does. Because the two standards use different reference populations and length is measured lying down before age 2 but standing after, a child's percentile can shift slightly at the 24-month switch without any real change in growth. Preterm babies are usually assessed using corrected age, and children with a medical condition may have their own charts — your clinician can advise.