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Child Nutritional Status Calculator (WHO Z-Score)

Check child nutrition status using WHO 2006 standards: weight-for-age, height-for-age, weight-for-height, and BMI-for-age with Z-scores.

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Comprehensive child nutritional-status calculator using WHO 2006 standards for ages 0-60 months. Covers four primary indicators plus an integrated summary.

Five tabs: weight-for-age (WAZ), height-for-age (HAZ), weight-for-height (WHZ — wasting screen), BMI-for-age (BAZ), and overall nutritional-status summary (severe / moderate / normal / overweight / obese) with intervention guidance.

Disclaimer: Z-score estimates use WHO 2006 tables. Consult a pediatrician or registered dietitian for diagnosis and intervention.

Toddler nutritional status assessment (0-60 months) based on 4 anthropometric indicators per WHO 2006 standards: WAZ, HAZ, WHZ, and BMI-for-age. The Summary tab aggregates all four indicators for a complete nutritional classification.

Weight-for-Age Z-score. Detects underweight or overweight conditions.

0-60 months (5 years)

About Child Nutritional Status

WAZ (Weight-for-Age): detects underweight; combines acute and chronic malnutrition signals.

HAZ (Height-for-Age): detects stunting from chronic malnutrition during the first 1,000 days.

WHZ (Weight-for-Height): detects wasting (acute malnutrition) and overweight independent of age.

BMI-for-Age: primary indicator for child obesity. Z-scores classified per WHO 2006 standards.

This calculator uses simplified WHO 2006 references for quick screening. Results are not a diagnosis. Consult a pediatrician, dietitian, or community health post for thorough evaluation and management.

Calculator information

How to use this calculator

  1. Select the child's sex (male/female) because WHO standards are sex-specific.
  2. Enter age in months (0-60), weight in kg (1 decimal), and length/height in cm.
  3. For children under 2 years (24 months), measure length lying down; for over 2 years, measure standing height.
  4. Choose the indicator you want to calculate: weight-for-age, height-for-age, weight-for-height, or BMI-for-age.
  5. Click Calculate for the Z-score, nutritional status category, and intervention guidance based on CDC and WHO recommendations.
  6. Use the Summary tab to view all four indicators together and see the integrated classification (stunting + wasting + underweight).

Z-Score from WHO Child Growth Standards (2006)

Z-score = ((value/M)^L - 1) / (L × S) if L ≠ 0 ; Z-score = ln(value/M) / S if L = 0
  • value = child's anthropometric measurement (weight, height, or BMI)
  • L = Box-Cox power parameter (skewness)
  • M = WHO reference median for the given age/height
  • S = coefficient of variation
  • Categories: <-3 SD = severely low; -3 to -2 SD = low; -2 to +1 SD = normal; +1 to +2 SD = at risk of overweight; >+2 SD = overweight/obese

Stunting = height-for-age <-2 SD. Wasting = weight-for-height <-2 SD. Underweight = weight-for-age <-2 SD. Obesity = BMI-for-age >+3 SD.

Worked example: Girl aged 24 months, weight 10 kg, height 82 cm

Given:
  • Sex: Female
  • Age: 24 months
  • Weight: 10.0 kg
  • Height: 82 cm
Steps:
  1. Median weight-for-age, girls 24 mo (M) = 11.5 kg; L = -0.1119; S = 0.10930
  2. Z weight-for-age = ((10/11.5)^(-0.1119) - 1) / (-0.1119 × 0.10930)
  3. = ((0.8696)^(-0.1119) - 1) / (-0.01223)
  4. = (1.01568 - 1) / (-0.01223) = -1.28 SD
  5. Median height-for-age, girls 24 mo = 85.7 cm, S = 0.04018, L = 1
  6. Z height-for-age ≈ (82/85.7 - 1) / 0.04018 = -0.0432 / 0.04018 = -1.07 SD

Result: Weight-for-age -1.28 SD = normal nutritional status. Height-for-age -1.07 SD = normal. Status: not stunted, not underweight. Continue monthly growth monitoring.

Frequently asked questions

What is the difference between stunting, wasting, and underweight?
Stunting = short for age (height-for-age <-2 SD), an indicator of chronic undernutrition, especially during the first 1,000 days. Wasting = thin for height (weight-for-height <-2 SD), an indicator of acute undernutrition. Underweight = low weight for age (weight-for-age <-2 SD), a composite of chronic and acute. Stunting can permanently affect IQ and adult productivity.
Why are WHO standards used instead of local standards?
The WHO Multicentre Growth Reference Study (2006) showed that children under 5 from six countries (Brazil, Ghana, India, Norway, Oman, USA) grew remarkably similarly when given exclusive breastfeeding, adequate complementary feeding, and a healthy environment. In other words, differences between populations are driven more by nutrition and environment than by genetics. The CDC recommends using WHO growth charts for U.S. children from birth to age 2 and switching to CDC charts after age 2.
How common is stunting in the U.S.?
Stunting is rare in the general U.S. population (~2-3%), but it is more common in low-income communities, among certain immigrant groups, and in children with chronic medical conditions. WHO classifies stunting under 2.5% as 'eliminated.' Priority interventions are nutrition during the first 1,000 days, exclusive breastfeeding through 6 months, adequate complementary feeding, and clean water and sanitation.
What should I do if a child is detected as undernourished?
Refer the child to a pediatrician or WIC clinic for confirmation and a tailored nutrition plan. For severe acute malnutrition (weight-for-height <-3 SD) without complications, clinicians follow WHO/CDC protocols using therapeutic feeds (F-75/F-100) or ready-to-use therapeutic food (RUTF). Investigate underlying causes: feeding patterns, chronic infections (TB, HIV), or congenital conditions. Monitor weight weekly.
How should I measure a child's length or height correctly?
Children under 2 (or shorter than 87 cm) are measured lying down (recumbent length) on a length board: head against the fixed headboard, knees straight, feet at right angles. Children 2 and older are measured standing (stature) with a stadiometer: heels, buttocks, and head against the wall, gaze on the Frankfort horizontal plane. The difference between length and stature is about 0.7 cm.

Last updated: May 11, 2026

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