Child wasting is defined as a weight-for-height/length z-score (WLZ/WHZ) < −2, and this indicator of nutritional status is used worldwide. However, a precise measurement is required for the assessment of a child's nutritional status, which may not always be possible due to expensive instruments, especially in poor resource settings. In some instances, mid-upper arm circumference-for-age z-score (MUACZ) is also being used for screening purposes, which is a simple and useful nutritional indicator. The objective of this paper is to identify the optimal cut-off point for the MUACZ to identify wasted children, and also to determine if the same factors are associated with MUACZ and wasting. Data were derived from the Suchana evaluation data. The optimal cut-off value was estimated via receiver operating characteristic (ROC) curve analysis using acute malnutrition as a gold standard with maximum sensitivity and specificity. Multiple logistic regression was used to assess the associated factors with the MUACZ. Using the gold standard indicator of nonwasting (WLZ ≥ −2), a positive outcome, the optimal cut-off point for the MUACZ was −1.27. The area under the ROC curve was 0.88, indicating that the model had a power of 88% to differentiate between the positive and negative classes. It implies that a child's MUACZ was correlated with WLZ, and a MUACZ below −1.27 appeared to accurately identify wasting among children aged 3–23 months. MUACZ < −1.27 might be another useful indicator of childhood wasting than a WLZ < −2.