Number Needed to Treat (NNT) Calculator
Calculate NNT, ARR, RRR, and other clinical measures from 2x2 data
Treatment Group:
Control Group:
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
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
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Formula Source: Standard Mathematical References
by Various
🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.