Calculate point or period prevalence per 100, 1,000 or 100,000 with an exact confidence interval, or estimate prevalence from incidence and duration.
About this tool
Point or period prevalence with confidence interval, or from incidence and duration.
How to use Prevalence Calculator
- Choose case counts, or incidence and duration.
- Enter the cases and population, or the incidence rate and average duration.
- Read the prevalence and its confidence interval.
Worked example
180 cases in a population of 2,400 is a prevalence of 75 per 1,000 (7.5%, 95% CI 6.48% to 8.63%).
How does duration affect prevalence?
In a steady state prevalence ≈ incidence × duration, so long-lasting conditions are more prevalent even at the same incidence.
Point or period prevalence?
Point prevalence counts cases on one date; period prevalence counts anyone affected during a period, such as a year.
- Prevalence Calculator — Point or period prevalence with confidence interval, or from incidence and duration.
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