Incidence & Prevalence Calculator

Calculate incidence rate, period prevalence, attack rate, and case fatality ratio from population data.

Calculate

New cases during period

Population at risk (start of period)

Time period (years)

FORMULA

Incidence Rate = (New cases / Population × Time) × 100,000

Total cases (existing + new)

Total population surveyed

FORMULA

Prevalence = (Total cases / Population) × 100,000

Cases among exposed group

Total exposed (at risk)

FORMULA

Attack Rate = (Cases / Exposed) × 100

Deaths from the disease

Confirmed cases of the disease

FORMULA

CFR = (Deaths / Cases) × 100

Enter values and click Calculate

For educational use. Source: Porta M (ed). A Dictionary of Epidemiology, 6th ed. Oxford University Press, 2014. Reviewed Sep 2026.