F1 Score Metric

What is F1 Score?

The F1 Score is the harmonic mean of precision and recall, providing a single metric that balances both.

Formula

F1 = 2 * (Precision * Recall) / (Precision + Recall)

Range

• 0 to 1: Higher is better
• 1.0: Perfect precision and recall
• 0.5: Moderate performance
• < 0.5: Poor performance

When to Use

• Imbalanced classes (one class has many more samples)
• When both false positives and false negatives are costly
• Classification problems where accuracy might be misleading

Related Terms

• Precision: True positives / predicted positives
• Recall: True positives / actual positives
• Accuracy: Overall correct predictions