This index indicates body weight at a given age. The child’s exact age must be known. In comparison to that of an average healthy child of the same age, it can identify underweight, but cannot differentiate between wasting and stunting. This index is commonly used in paediatric clinics, but it may not be feasible, for example, for unaccompanied children in refugee situations.

If a child has a low weight-for-age, you will need to check the child’s height-for-age and weight-for-height to see if the child is stunted and/or wasted. On the right, there are three children highlighted. Click each child to see their height-for-age and weight-for-height. You will see that the child -2SD weight-for-age is of normal height but is wasted. The child with median weight-for-age (0 SD) is stunted and overweight. The child +2 SD weight-for-age is tall but of normal weight-for-height (i.e. is not wasted or overweight). Children with oedema have increased body weight due to fluid retention, and their true weight is masked. Weight-for-age and weight-for-height are overestimated in children with oedema. Children with oedema are considered to be severely malnourished regardless of their weight-for-age or weight-for-height SD score.