What's the difference between typical use and perfect use?

Typical use means how well the method works to prevent pregnancy when real people in real life use it, whereas perfect use means how well the method works when it's being tested in a clinical trial by people who are following the instructions perfectly every time for a whole year A perfect use effectiveness rate of 99%, for example, would mean that over the course of a year, on average, 1 out of 100 people using this method exactly as instructed will get pregnant.

Since life isn't a clinical trial, we recommend paying closer attention to typical use numbers. But you can get closer to the perfect use number by learning to use your method correctly and consistently.