Odds Ratio and Relative Risk Calculator
Compare two observed groups using risk ratio, odds ratio and absolute risk difference from a two-by-two count table.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Add event and non-event counts within each group. Divide event counts by their group totals. Compare those proportions for relative risk and risk difference. Form the cross-product odds ratio when its denominator is nonzero.
RR=[a/(a+b)]/[c/(c+d)]; OR=ad/(bc); RD=a/(a+b)−c/(c+d)
Worked example
Counts 20 and 80 in group A versus 10 and 90 in group B give RR 2, OR 2.25 and a 10 percentage-point risk difference.
Assumptions and input details
Descriptive observed associations only, without confidence intervals or causal interpretation. Case-control sampling does not generally identify population risks. Zero denominators remain undefined; no continuity correction is silently added.
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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