Failure to thrive (FTT) is a perplexing disorder commonly seen by primary care physicians. Identification of FTT and an assessment of severity of the undernutrition are important to identify children at risk, and to provide appropriate intervention for preventing malnutrition and developing sequela. One of different anthropometric methods for categorizing undernutrition in childhood is Waterlow and Gomez classifications. Unfortunately, these classifications are not an easy task for the practitioners due to its difficult calculations. In this paper, Waterlow and Gomez classifications have been shown on the Standard Growth Charts (WHO 2006). Using these curves, the practitioners can determine severity of FTT by plotting weight, height and age of the patients without any calculations.