NNH Calculator

Free calculate NNH (Number Needed to Harm). This is an educational tool only - always consult a healthcare provider.

Adverse Event Rates

Percentage of control group with adverse event

Percentage of treatment group with adverse event

Results

Enter adverse event rates to calculate NNH

About NNH

  • • NNH = 1 / (EER - CER)
  • • Higher NNH = safer treatment
  • • NNH >100: Very safe
  • • NNH 50-100: Relatively safe
  • • NNH <50: Higher risk