# Incidence Rate Calculator

Determines the number of new cases of disease during a specified time interval based on population at risk and population size.

Incidence Rate is one measure of morbidity frequency often used in epidemiology to characterize the number of new cases of disease during a specified time interval.

`Incidence Rate = Total no. of new cases of disease / Total population at risk x Population size`

Usually, in epidemiology, population size is taken by default as 100,000.

Total number of new cases of disease
Total population at risk
Population size
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Steps on how to print your input & results:

2. Then you can click on the Print button to open a PDF in a separate window with the inputs and results. You can further save the PDF or print it.

Please note that once you have closed the PDF you need to click on the Calculate button before you try opening it again, otherwise the input and/or results may not appear in the pdf.

## Incidence Rate Formula

Incidence Rate is one measure of morbidity frequency often used in epidemiology to characterize the number of new cases of disease during a specified time interval (the numerator) and summed person-years of observation or average population during time interval (the denominator).

`Incidence Rate = Total no. of new cases of disease / Total population at risk x Population size`

In some publications, epidemiologists may use incidence to mean the number of new cases in a community whilst in others, it means the number of new cases per unit of population.

During a research study, each person is observed from an established starting time until one of four “end points” is reached: either onset of disease, exitus, migration out of the study or end of study.

In the calculator above, the population size may be chosen from the following options: 1,000 | 10,000 | 100,000 | 1,000,000 or customized as per individual needs.

## References

Spronk, I., Korevaar, J.C., Poos, R. et al. Calculating incidence rates and prevalence proportions: not as simple as it seems. BMC Public Health 19, 512 (2019).

S Giampaoli, L Palmieri, R Capocaccia, L Pilotto, D Vanuzzo, Estimating population-based incidence and prevalence of major coronary events. International Journal of Epidemiology, Volume 30, Issue suppl_1, Oct 2001, Page S5–10.

Specialty: Epidemiology

Article By: Denise Nedea

Published On: October 22, 2020

Last Checked: October 22, 2020

Next Review: October 22, 2025