Number Needed to Treat (NNT) Calculator

Calculate NNT, ARR, RRR, and other clinical measures from 2x2 data

Treatment Group:

Events (treatment):

Total N (treatment):

Control Group:

Events (control):

Total N (control):

About NNT

NNT: Number of patients to treat to prevent 1 additional bad outcome.

NNH: Number of patients to treat before 1 is harmed.

ARR: Control Rate - Treatment Rate

NNT: 1 / ARR

Lower NNT = more effective treatment