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 when they didn’t want to.

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 all the time.

Some methods, like the IUD and implant, have a typical use rate that is super close to their perfect use rate—that’s because there’s very little room for error since there’s nothing to do or remember besides getting it switched out for a new one when it’s time. Methods you have to remember to use every time you have sex, like condoms or the pull-out method](/birth-control/withdrawal), have a bigger difference between their typical use rate and perfect use rates because there’s lots more room for error.