https://en.wikipedia.org/wiki/Comparison_of_birth_control_methods#Effectiveness https://en.wikipedia.org/wiki/Comparison_of_birth_control_me... No contraceptiv

https://en.wikipedia.org/wiki/Comparison_of_birth_control_methods#Effectiveness https://en.wikipedia.org/wiki/Comparison_of_birth_control_me... No contraceptive is perfect, and the rates vary between methods. Note that some of the methods in the table can be combined (and often are), thus lowering the overall chance of pregnancy. ars's comment seems a bit extreme; while condoms don't perfectly prevent pregnancy, they are certainly quite effective at reducing the chance of it.