Attack Rate Calculator

Summary

Calculate attack rates for exposed and unexposed groups, relative risk, and attributable risk during outbreak investigations.

How it works

1. Enter the number of people who became ill among those exposed to the suspected source.
2. Enter the total number of people exposed to the suspected source.
3. Enter the number of people who became ill among those not exposed.
4. Enter the total number of people not exposed.
5. Click Calculate to see attack rates for each group, relative risk, and attributable risk.
6. Review the 2x2 contingency table for a full summary of the data.

Use cases

• Investigate foodborne illness outbreaks at restaurants or events.
• Assess the risk associated with a specific exposure in a cohort study.
• Determine whether a suspected food item or source is statistically linked to illness.
• Calculate relative risk to compare disease rates between exposed and unexposed groups.
• Compute attributable risk to estimate the excess risk due to exposure.
• Support field epidemiology reports and outbreak summary documentation.
• Train students and public health workers in basic epidemiologic calculations.
• Cross-check manual calculations for accuracy during rapid outbreak response.

Frequently Asked Questions