Number Needed to Treat Calculator

Control Event Rate (%)

Experimental Event Rate (%)

Events in Treatment

Total in Treatment

Events in Control

Total in Control

Formula

NNT = 1 / |CER - EER| = 1 / ARR

What is NNT?

Number Needed to Treat is the number of patients who must receive treatment for one additional patient to benefit. Lower NNT = more effective.

Free relative risk calculator. Calculate risk ratio, confidence interval, and attributable risk from a 2x2 table.

Free odds ratio calculator. Calculate odds ratio, confidence interval, and interpretation from a 2x2 contingency table.

Free survival rate calculator. Calculate cumulative survival probability over multiple time periods using the Kaplan-Meier method.