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Accuracy vs F1 Score

Accuracy — at a glance

Category: Evaluation · Difficulty: Beginner

The fraction of predictions a model gets correct on a labeled dataset.

Accuracy = (correct predictions) / (total predictions). Simple and intuitive, but misleading when classes are imbalanced — predicting 'no fraud' on every transaction can achieve 99% accuracy while being useless. Pair it with precision, recall, and F1 for a fuller picture.

Read the full Accuracy definition →

F1 Score — at a glance

Category: Evaluation · Difficulty: Beginner

The harmonic mean of precision and recall, balancing both into a single number.

F1 = 2·P·R / (P+R). It punishes models that score high on only one of precision or recall, making it a popular choice for imbalanced classification. Variants include macro-F1 (average per class) and weighted-F1.

Read the full F1 Score definition →

Key differences

  • Purpose: Accuracy is typically used for evaluation problems, while F1 Score fits evaluation use cases.
  • Complexity: Accuracy is rated Beginner; F1 Score is rated Beginner.
  • Definitions: The fraction of predictions a model gets correct on a labeled dataset. vs The harmonic mean of precision and recall, balancing both into a single number.

Frequently asked questions

What is the difference between Accuracy and F1 Score?

Accuracy: The fraction of predictions a model gets correct on a labeled dataset. F1 Score: The harmonic mean of precision and recall, balancing both into a single number.

When should I use Accuracy instead of F1 Score?

Use Accuracy when your problem matches its strengths: The fraction of predictions a model gets correct on a labeled dataset. Use F1 Score when The harmonic mean of precision and recall, balancing both into a single number.

Can Accuracy and F1 Score be used together?

Yes — many modern AI systems combine Accuracy and F1 Score to get the strengths of both approaches.

Is Accuracy better than F1 Score?

Neither is universally better. The right choice depends on data, latency, cost, and task. This page breaks down the trade-offs.