Enter the probability of events in the treatment group and the probability of events in the control group into the Hazard Ratio Calculator. The calculator will evaluate and display the Hazard Ratio.

## Hazard Ratio Formula

The following formula is used to calculate the Hazard Ratio.

HR = P(t) / P(c)
• Where HR is the Hazard Ratio ( )
• P(t) is the probability of events in the treatment group
• P(c) is the probability of events in the control group

To calculate a hazard ratio, divide the probability of the event in the treatment group by the probability of the events in the control group.

## How to Calculate Hazard Ratio?

The following example problems outline how to calculate Hazard Ratio.

Example Problem #1:

1. First, determine the probability of events in the treatment group.
• The probability of events in the treatment group is given as: .89.
2. Next, determine the probability of events in the control group.
• The probability of events in the control group is provided as: .95.
3. Finally, calculate the Hazard Ratio using the equation above:

HR = P(t) / P(c)

The values given above are inserted into the equation below and the solution is calculated:

HR = .89 / .95 = .93

Example Problem #2:

For this problem, the variables required are provided below:

probability of events in the treatment group = .75

probability of events in the control group = 1.25