How effective is withdrawal at preventing pregnancy?

If the partner with a penis pulls out perfectly every single time and no semen gets on the vulva or vagina, then withdrawal is about 96% effective. This is a hard method to get perfect, though, so it’s more likely that withdrawal will be around 80% effective in real life.

In other words:

For people who use withdrawal perfectly every single time for a whole year, about 4 in 100 will get pregnant when they don’t want to during the first year they use the pull-out method.

For people who use withdrawal as people typically use it, about 20 in 100 will get pregnant when they don’t want to during the first year they use the pull-out method.