Incidence Calculator
Cumulative incidence (risk) with an exact confidence interval.
Enter your values to see the result.
Confidence intervals use exact (Clopper–Pearson or Poisson) methods. Rates are only comparable between populations with similar age structures unless you standardize them.
Processing and privacy
Processing varies by tool. Check the instructions for local processing, server requests, external services and any file or request limits before entering sensitive information.
Read the privacy policyHow this calculation works
Understand the method, inputs and limits behind your result.
- Formula
- Cumulative incidence = new cases / population at risk × selected multiplier. Confidence intervals use the exact binomial method.
- Variables
- New cases during the period
- Population at risk at the start. Exclude people who already had the condition.
- Express per: 100 people (percent), 1,000 people, 10,000 people, 100,000 people
- Confidence level: 90%, 95%, 99%
- Units
- Use the units shown beside each input. Counts and ratios are dimensionless unless labeled otherwise.
- Example
- 45 new cases among 3,000 people at risk is a cumulative incidence of 15 per 1,000 (95% CI 10.96 to 20.02).
- Assumptions
- Confidence intervals use exact (Clopper–Pearson or Poisson) methods. Rates are only comparable between populations with similar age structures unless you standardize them.
- Source
- ToolzHive calculation guide and calculator implementation. External reference verification is pending.
- Last reviewed
- Review date not yet recorded.
Methodology & References
The method depends on the selected model and input options. Review the assumptions and references above before interpreting the result.
- Enter the number of new cases during the period.
- Enter the population at risk at the start.
- Choose the multiplier and read the incidence with its interval.
Interpretation and limitations
- What is the difference between incidence and prevalence? Incidence counts new cases over a period; prevalence counts everyone who has the condition at a point in time.
- Who is “at risk”? People who could develop the condition during the period, so exclude those who already have it or cannot get it.
References
External reference verification is pending. The formula and examples describe the current ToolzHive implementation.
Share this tool
Found it useful? Send it to a friend or teammate.
Rate this tool
0.0
0 ratings
- 5 stars 0
- 4 stars 0
- 3 stars 0
- 2 stars 0
- 1 star 0
Clear instructions
Find steps, examples and limitations below.
Use online
Open the tool in a supported web browser.
Free to use
No sign-up required. Tool-specific limits may apply.
How to use the Incidence Calculator
Cumulative incidence (risk) with an exact confidence interval.
- 1 Enter the number of new cases during the period.
- 2 Enter the population at risk at the start.
- 3 Choose the multiplier and read the incidence with its interval.
Example and practical tips
45 new cases among 3,000 people at risk is a cumulative incidence of 15 per 1,000 (95% CI 10.96 to 20.02).
Frequently asked questions
What is the difference between incidence and prevalence?
Incidence counts new cases over a period; prevalence counts everyone who has the condition at a point in time.
Who is “at risk”?
People who could develop the condition during the period, so exclude those who already have it or cannot get it.
Practical guides
-
How to Use Incidence Calculator
Calculate cumulative incidence (risk) of new cases in a population at risk per 100, 1,000 or 100,000 people with an exact Clopper–Pearson confidence interval.
Report an issue
Something broken or not quite right? Tell us and we will look into it.