Attributable Risk Calculator
Enter incidence counts for exposed and unexposed groups to instantly calculate attributable risk, relative risk, and population-level impact.
2x2 Epidemiology Table
Enter case counts and group totals for exposed and unexposed populations.
Exposed Group
Unexposed Group
Fill in the 2x2 table and click Calculate to see results.
Incidence Rates
Exposed (Ie)
—
per 1,000
Unexposed (Iu)
—
per 1,000
Key Metrics
Attributable Risk (AR)
Ie − Iu — excess cases per 1,000 due to exposure
—
per 1,000
Attributable Risk % (AR%)
AR / Ie — fraction of exposed cases caused by exposure
—
%
Relative Risk (RR)
Ie / Iu — times more likely to develop disease
—
ratio
Population Attributable Risk (PAR)
Itotal − Iu — excess cases in entire population
—
per 1,000
Interpretation
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Summary
Enter incidence counts for exposed and unexposed groups to instantly calculate attributable risk, relative risk, and population-level impact.
How it works
- Enter the number of cases (disease events) observed in the exposed group.
- Enter the total number of individuals in the exposed group.
- Enter the number of cases in the unexposed (control) group.
- Enter the total number of individuals in the unexposed group.
- The calculator derives incidence rates and applies standard epidemiological formulas.
- Results update instantly — copy them or adjust inputs to explore scenarios.
Use cases
- Assess how much excess disease risk is attributable to a specific environmental or behavioral exposure.
- Compare relative risk between exposed and unexposed cohorts in observational studies.
- Estimate the proportion of cases that could be prevented by eliminating the exposure (AR%).
- Calculate population attributable risk to guide public health intervention priorities.
- Validate hand-calculated values from epidemiology coursework or research papers.
- Perform sensitivity analysis by adjusting case counts to explore best- and worst-case scenarios.
- Prepare summary statistics for academic papers, grant applications, or clinical reports.
- Teach epidemiology concepts interactively in a classroom or workshop setting.
Frequently Asked Questions
Last updated: 2026-06-09 ·
Reviewed by Nham Vu