# Number Needed to Treat Calculator (NNT)

Enter the control group % and the experiment group % into the NNT calculator. The calculator will display the total number of patients that need to be treated to achieve an endpoint.

## Number Needed to Treat Formula

The following formula is used to calculate the total number of patients that need to be treated in order to achieve a result.

NNT=1/ARR

• Where NNT is the number of patients that need to be treated
• ARR is the absolute risk reduction

Further more, ARR can be calculated through the following equation.

ARR=CER – EER

• Where CER is the control event rate
• EER is the experiment event rate

How to calculate a number needed to treat

1. First, measure the control event rate

This will be the percent treated in the control event.

2. Next, measure the experiment event rate

This will be the percent treated in the experiment.

3. Lastly, calculate the NNT

Using the formula above and the information from steps 1-2 to calculate the NNT

## FAQ

What is NNT?

NNT stands for number needed to treat. It’s a term used in medicine to describe the total number of patients needed to be treated in order to achieve a given result.