How effective is the pill at preventing pregnancy?

How effective the pill is at preventing pregnancy depends on what type of pill you are using and how consistently you take it. When used perfectly, the pill is more than 99% effective. But most of us aren’t perfect, so the pill’s effectiveness tends to be closer to 93%.

In other words:

For people who use the combination pill exactly as directed for a whole year, fewer than 1 in 100 will get pregnant when they don’t want to during the first year of using the pill. If you are using the progestin-only, mini-pill, it’s slightly less effective—98% with perfect use.

For people who do not use their pill exactly as directed (either kind), about 7 in 100 will get pregnant when they don’t want to during the first year of using the pill.