Cross-Entropy Loss

Cross-Entropy Loss

Cross-Entropy Loss, also known as Log Loss, is a crucial concept in the field of machine learning and deep learning. It is a popular loss function used in various classification problems, including binary and multi-class classification.


Cross-Entropy Loss is a performance metric that quantifies the difference between the actual and predicted probability distributions in classification tasks. It measures the dissimilarity between the ground truth (actual labels) and the estimated probabilities (predicted labels). The lower the Cross-Entropy Loss, the better the model’s performance.

How it Works

In binary classification, the Cross-Entropy Loss for a single instance can be calculated using the formula:

Cross-Entropy Loss = -[y*log(p) + (1-y)*log(1-p)]


  • y is the actual label (0 or 1)
  • p is the predicted probability of the instance being in class 1

For multi-class classification, the formula extends to:

Cross-Entropy Loss = - Σ(y*log(p))


  • y is a binary indicator (0 or 1) if class label c is the correct classification for observation o
  • p is the predicted probability observation o is of class c

Importance in Machine Learning

Cross-Entropy Loss is widely used in machine learning due to its effectiveness in handling probabilistic predictions. It penalizes the models that output incorrect probabilities, thus pushing the model towards accurate predictions.

Use Cases

Cross-Entropy Loss is commonly used in various machine learning algorithms, including logistic regression, neural networks, and decision trees. It is particularly effective in training deep learning models for tasks such as image classification, natural language processing, and speech recognition.

Advantages and Disadvantages


  • It is effective in handling probabilistic predictions.
  • It penalizes models that are confident about an incorrect prediction.


  • It can lead to overfitting if the model becomes too confident about its predictions.
  • It is sensitive to outliers as it tries to correctly classify every instance.
  • Log Loss: Another name for Cross-Entropy Loss, often used interchangeably.
  • Binary Cross-Entropy Loss: A type of Cross-Entropy Loss used specifically for binary classification problems.
  • Categorical Cross-Entropy Loss: A type of Cross-Entropy Loss used for multi-class classification problems.

Further Reading


  1. Goodfellow, I., Bengio, Y., & Courville, A. (2016). Deep Learning. MIT Press.
  2. Bishop, C. M. (2006). Pattern Recognition and Machine Learning. Springer.