Multiclass accuracy is a machine learning evaluation metric that measures the proportion of correct predictions made by a model across a classification problem involving three or more mutually exclusive categories. In standard evaluation, it is calculated as the total number of correctly predicted instances divided by the overall number of samples, reflecting overall model correctness across all classes. In contexts with imbalanced datasets, multiclass accuracy can also be evaluated as the mean of the accuracies achieved on each individual category, ensuring that performance on underrepresented classes contributes equally to the final score.