Free tools
Free clinical & study tools
No account required. The math clinical reasoning and evidence appraisal actually run on.
NNT Calculator
Number needed to treat, absolute and relative risk reduction.
Likelihood Ratio Calculator
LR+ and LR− from sensitivity and specificity, with interpretation.
Pretest/Posttest Probability
The Bayesian update behind test interpretation.
PICO Question Builder
Build a well-formed, searchable clinical question.