Number Needed to Harm (NNH)
Calculate Number Needed to Harm (NNH) instantly with the exact formula and a worked example. Free online calculator — no signup, works on mobile.
Number Needed to Harm (NNH)
1 / ARI
NNH
50
More about: Number Needed to Harm (NNH)
What it calculates
The “Number Needed to Harm (NNH)” calculator computes NNH from 1 parameter: 1 / ari.
A core calculation for studying, engineering tasks, and checking solutions.
Example calculation
With parameters 1 / ARI = 50 the result is 50.
How to use
- Enter the parameter values — every field above is adjustable with a slider.
- The result and related metrics are calculated automatically as you type.
- Use the additional metrics shown (if any) where needed.
- Copy the result or bookmark the page.