Work out contraceptive effectiveness instantly with clear inputs, formula shown and shareable results.
Compounds published first-year failure rates over the chosen number of years so typical and perfect use can be compared over a realistic horizon.
Cumulative failure
Cumulative pregnancy risk = 1 - (1 - annual failure rate)^years
Educational estimate only. Not a substitute for professional clinical judgement, and must not be used to make treatment or dosing decisions.
Methods needing daily or per-act action are vulnerable to missed doses; long-acting methods have almost no gap.
For most methods yes, as users become more consistent, so a constant-rate model is conservative.