Hazard Ratio
Calculate Hazard Ratio instantly with the exact formula and a worked example.
Hazard Ratio
Events in treatment group
Person-time in treatment groupperson-years
Events in control group
Person-time in control groupperson-years
HR
0.6
95% CI
0.38–0.94
Rate per 1000 person-years (treatment)
30
Rate per 1000 person-years (control)
50
Conclusion
Risk significantly lower
More about: Hazard Ratio
What it calculates
The “Hazard Ratio” calculator computes HR from 4 parameters: events in treatment group, person-time in treatment group (person-years), events in control group, person-time in control group (person-years).
A core calculation for studying, engineering tasks, and checking solutions.
Example calculation
With parameters Events in treatment group = 30, Person-time in treatment group = 1,000 person-years, Events in control group = 50, Person-time in control group = 1,000 person-years the result is 0.6 (Estimate assumes constant hazard over time; an exact HR needs a Cox model).
How to use
- Enter events in treatment group, person-time in treatment group, events in control group and person-time in control group — each field above is adjustable with a slider.
- HR is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
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FAQ
How is Hazard Ratio calculated?
The Hazard Ratio calculator computes HR from events in treatment group, person-time in treatment group, events in control group, person-time in control group. Enter your values above and the exact formula is applied instantly; a worked example with real numbers is shown below.
Is the Hazard Ratio calculator free?
Yes. It is completely free, needs no signup, runs entirely in your browser, and sends no data to any server.
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