F1 Score Calculator
F1 combines precision and recall into one harmonic-mean score for positive predictions. It is commonly used when false positives and false negatives both matter.
How to use this calculator
- Enter integer true-positive, false-positive and false-negative counts.
- Check that all inputs use the same units, period and population scope.
- Change one assumption at a time when comparing scenarios.
Formula used by f1 score calculator calculator
Precision = TP/(TP+FP); recall = TP/(TP+FN); F1 = 2TP/(2TP+FP+FN).
- Precision = TP/(TP+FP); recall = TP/(TP+FN); F1 = 2TP/(2TP+FP+FN).
- F1 ignores true negatives and does not represent calibrated probabilities. Choose metrics aligned to actual error costs and prevalence.
- The tool validates inputs and rounds displayed figures for readability; it does not validate assumptions against external records.
Worked examples
Worked example
There are 80 true positives, 20 false positives and 15 false negatives.
F1 = 160 ÷ (160 + 20 + 15) ≈ 0.8205.
The F1 score is approximately 0.8205.
Understanding the result
F1 combines precision and recall into one harmonic-mean score for positive predictions. It is commonly used when false positives and false negatives both matter.
F1 ignores true negatives and does not represent calibrated probabilities. Choose metrics aligned to actual error costs and prevalence.
Important notes
F1 ignores true negatives and does not represent calibrated probabilities. Choose metrics aligned to actual error costs and prevalence.
Treat the result as an estimate from the entered assumptions. For commercial, statistical, engineering or health-related decisions, verify relevant specifications and professional guidance.
Frequently asked questions
Can F1 be a percentage?
It ranges from 0 to 1; multiplying by 100 expresses it as a percentage-like score.
Can F1 replace precision and recall?
It compresses them into one measure, but both underlying values should still be reviewed.
How should I interpret this result?
F1 ignores true negatives and does not represent calibrated probabilities. Choose metrics aligned to actual error costs and prevalence.
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Related explanations
Learn the method behind the number or compare the terminology before using the calculator.
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This page provides a calculation tool plus explanatory information so you can understand what the result means and when the underlying method may not fit your situation.