Enter the total amount of people with a disease and without of two separate groups; one being the exposed group and one being the control. The calculator will determine the relative risk.

## Relative Risk Formula

The following equation can be used to calculate the relative risk of two groups of people.

R = [ a / (a+b)] / [c/(c+d))]

• Where R is the relative risk
• a is the number of people in the exposed group with a disease
• b is the number of people in the exposed group without the disease
• c is the number of people in the control or base group with the disease
• d is the number of people ins the control group without the disease

## Relative Risk Definition

Relative risk measures the risk ratio of one group to another. In other words, it compares how many people get a particular disease when exposed to an outside factor with respect to a control group not exposed to that factor.

## Relative Risk Example

How to calculate the relative risk?

1. First, determine the number of people with the disease in the exposed group

Measure variable a from the formula above.

2. Next, determine the number of people without the disease in the exposed group.

Measure variable b from the formula above.

3. Next, determine the number of people with the disease in the control group.

Measure variable c from the formula above.

4. Next, determine the number of people without the disease in the control group.

Measure variable d from the formula above.

5. Finally, calculate the relative risk.

Calculate the relative risk using the equation.

## FAQ

What is relative risk?

A relative risk is a ratio of the risk of contracting a disease based on exposure compared to a control group.