WAZ Calculator - Weight-for-Age Z-Score (Underweight)
Calculate weight-for-age z-score (WAZ) to assess underweight status in children 0–60 months using WHO Child Growth Standards.
Weight-for-age z-score (WAZ) is used to classify underweight status in children from birth to 60 months. It compares a child’s weight to the WHO reference median for their age and sex, expressing the difference in standard deviations. WAZ captures both acute and chronic undernutrition but cannot distinguish between them; a child may be underweight due to wasting, stunting, or both. Enter the child’s age in completed months, sex, and current weight to calculate.
| WAZ | Classification | Action |
|---|---|---|
| < −3 | Severely underweight | Refer for therapeutic nutrition support; assess for wasting and stunting |
| −3 to < −2 | Underweight (moderate) | Enrol in supplementary feeding; increase monitoring frequency |
| −2 to +2 | Normal weight-for-age | Routine growth monitoring |
| > +2 | Overweight risk | Dietary and feeding practice counselling |
Source: WHO Multicentre Growth Reference Study Group (2006). WHO Child Growth Standards: Length/height-for-age, weight-for-age, weight-for-length, weight-for-height and body mass index-for-age. Geneva: World Health Organization.