Compare calculators

Both calculators run independently — change the inputs on either side to compare results.

Number Needed to Treat (NNT) Calculator

Calculate the number of patients who must be treated to prevent one additional bad outcome, from the control and treatment event rates. A key measure of clinical effectiveness.

Control Group Event Rate (%)

Treatment Group Event Rate (%)

Statistics

Odds Ratio Calculator

Compute the odds ratio from a 2×2 contingency table to measure the association between an exposure and an outcome. Widely used in epidemiology and case-control studies.

Exposed, with outcome (a)

Exposed, no outcome (b)

Unexposed, with outcome (c)

Unexposed, no outcome (d)

Key differences

	Number Needed to Treat (NNT) Calculator	Odds Ratio Calculator
Category	Statistics	Statistics
Inputs required	2	4
Result	Number Needed to Treat (patients)	Odds Ratio
What it does	Calculate the number of patients who must be treated to prevent one additional bad outcome, from the control and treatment event rates. A key measure of clinical effectiveness.	Compute the odds ratio from a 2×2 contingency table to measure the association between an exposure and an outcome. Widely used in epidemiology and case-control studies.