F Distribution Calculator
Evaluate the F-distribution CDF, upper tail and mean where defined.
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Result
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Calculation steps
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How to calculate
Map the positive F ratio to the regularized beta CDF with distinct numerator and denominator degrees of freedom.
CDF=I[(d1 F)/(d1 F+d2)](d1/2,d2/2)
Worked example
F=1 with equal numerator and denominator degrees of freedom has CDF 0.5. For denominator df >2, mean is df/(df−2).
Assumptions and input details
No data fitting or variance-test choice is performed. The mean is undefined for denominator df≤2 and variance is undefined for df≤4. Extreme tails can round to zero.
References: NIST: probability distributions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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