Calculate weight, recumbent length or standing height, BMI and head-circumference percentiles by exact age and sex. U.S. recommended mode supports birth through 20 years; WHO international mode supports birth through 19 years, subject to measurement-specific limits.
Corrected age subtracts time born before 40 weeks. Use commonly varies until about age 2 and requires professional interpretation.
WHO 2007 weight-for-age ends at 10; height and BMI continue to 19. Head circumference ends at 5.
Automatic uses length below age 2 and height afterward. An override applies and discloses the WHO 0.7 cm conversion.
A percentile compares this measurement with same-age, same-sex children in the selected reference. It is not a grade, goal or diagnosis. A steady pattern and overall health matter more than one point.
Consistently measured points show whether growth broadly tracks a curve. Saved entries never leave this browser.
Male, exactly 9 months; 9.70 kg, 72.0 cm recumbent length and 45.0 cm head circumference. U.S. mode selects WHO 2006. BMI is not reported before age 2 in U.S. mode.
Results load with the data.
Female, exactly 10 years; 32.0 kg and 138.0 cm standing height. Intermediate BMI = 16.80 kg/m². U.S. mode selects CDC 2000.
Results load with the data.
For U.S. use, CDC and the AAP recommend WHO before age 2 and CDC from age 2. International mode uses WHO 2006 daily rows through age 5 and WHO 2007 monthly rows from completed month 61 through 19.
Recumbent length is standard below age 2; standing height is standard afterward. When the other method is chosen the calculator applies a 0.7 cm adjustment and labels it.
Healthy children can be at many percentiles. Sustained change may reflect technique, normal catch-up growth, illness, nutrition, puberty or another factor.
Remeasure an unexpected value with stable equipment. Consult a qualified clinician about feeding, growth, development, rapid change or illness; do not delay care because of this tool.
After the plain-language result, the engine uses L (skew), M (median) and S (spread): ((X/M)^L−1)/(L×S), or ln(X/M)/S when L is zero.
The 50th is the median. The 3rd means about 3 in 100 reference children have a lower value; the 97th means about 97 in 100 do. All are comparisons, not grades.
No. Family pattern, gestation, health, puberty, measurement quality and change over time matter. Ask a clinician if concerned.
Reference choice, exact or corrected age, rounding, length/height method, units, equipment and software version can differ.
Choose U.S. recommended for the WHO-to-CDC transition at age 2; choose WHO international when WHO 2006/2007 is appropriate locally.
It subtracts the time from gestational age at birth to 40 weeks while chronological age is under 2. Professional practice varies.
Length is measured lying down and is slightly greater than standing height. The calculator expects length below 2 and height afterward.
U.S. mode reports BMI-for-age from age 2, when CDC child BMI categories apply. WHO BMI exists earlier but needs careful interpretation.
Small changes are common. Check technique and several dated points. Discuss sustained or large change with a clinician.
Follow your health service’s schedule. Very frequent measuring can magnify normal noise; consistent technique matters.
Nothing is uploaded. A visit is stored locally only after “Save to trend,” and “Delete all history” removes it.
Maintainer: Starlight Tools Editorial Team · Medical reviewer: no named medical reviewer appointed; informational use only. Last reviewed: 18 July 2026 · Method version: 2026.07.
| Reference | Implemented coverage | Source |
|---|---|---|
| WHO 2006 | Weight, length/height, BMI and head circumference; birth–day 1,826 (the 5-year boundary); daily LMS rows. | WHO standards; WHO Anthro 1.1.0 tables for weight, length/height, BMI and head circumference |
| WHO 2007 | Height and BMI 61–228 months; weight 61–120 months; monthly LMS rows. | WHO 5–19 indicators |
| CDC 2000 | Weight and stature from 24 to under 240 months; BMI from 24 through 240 months; published monthly bins. U.S. mode uses WHO head circumference before 2. | CDC LMS files for weight, stature and BMI; documentation |
Age, interpolation and rounding: date mode uses local calendar dates and exact elapsed days. WHO 2006 uses the exact daily row; WHO 2007 uses the nearest published monthly row and CDC uses its published age bins. WHO’s supplied tables have no row after day 1,826 until completed month 61, so WHO international mode reports that brief transition interval as unavailable rather than clamping an endpoint. Percentiles display to one decimal and z-scores to two.
Limitations: No weight-for-length/height, velocity, genetic-potential or puberty assessment. CDC extended BMI above the 95th percentile is not implemented. Implausible inputs are rejected, but the calculator cannot detect poor technique.
Validation: startup checks require every table and expected boundary rows. Fixtures cover the visible WHO infant and CDC child examples, boundary ages, units and invalid values.
