Both combination and progestin-only birth control pills are 99 percent effective if you take them perfectly. But with typical (or imperfect) use, the pill’s effectiveness can drop to 91 percent — and most of us aren’t perfect.

So, if you’re not planning for a bébé anytime soon, how do you know if your birth control is really working… and exactly how effective are these percentages when it comes to real-life people?

Before you get physical, let’s get factual. Here’s how effective hormonal birth control pills and other contraception actually are at preventing pregnancy.

The combination pill combines estrogen and progestin to stop ovulation and thicken cervical mucus, which makes it harder for sperm to wiggle their way through the uterus to an egg.

The progestin-only pill — also known as the “minipill” — only uses the hormone progestin to thicken the cervical mucus and thin the lining of your uterus. But it doesn’t always suppress ovulation.

The minipill is usually recommended for specific circumstances, like if you’re breastfeeding, have concerns about taking estrogen, or if you’re taking certain meds or have certain health conditions. Progestin-only pills are also sometimes prescribed to help treat heavy periods or even migraine.

But even though both hormonal birth controls are pretty effective, it’s easier for the minipill to fail with imperfect use.

In people numbers, 99 percent effective means 1 out of 100 people will get pregnant every year when using birth control pills perfectly. And 91 percent effective means 9 out of 100 people will get pregnant with imperfect use.

Perfect use refers to taking your pills correctly every 👏 single 👏 time 👏. Consistency is super important when it comes to the pill. This generally means:

  • taking it at the same time, every day
  • preparing for outside factors that may make the pill less effective (aka having a backup birth control method ready)

But because “perfect” isn’t always realistic, it’s easy to slip up from time to time. Typical use is when you’re not using your BC correctly (at least not all the time). This could mean forgetting a dose or taking it at the wrong time.

According to Planned Parenthood, the progestin-only pill becomes ineffective if you miss your scheduled dose by 3 or more hours (with the exception of Slynd).

Technically, you don’t have to take combination pills at the same time every day, just taking 1 pill every day protects you. And if you missed a pill, the ineffectiveness may vary depending on the type of pill. Still, it’s a good habit to take any birth control pill at the same time. So set those alarms!

Generally speaking, both combination and progestin-only pills can become less effective if you:

  • miss or skip a dose
  • aren’t consistent on *when* you take it (remember: even a 3-hour delay can make most progestin-only pills ineffective)
  • are taking certain medications or antibiotics (specifically rifampin) that decrease birth control’s effectiveness.
  • have overweight
  • throw up within a 2-hour window of taking a dose

How long it takes birth control pill to work can depend on a lot of things — particularly when in your menstrual cycle you decide to start taking it.

If you take your first dose of a combination pill on days 1 through 5 of your period, you’ll experience max effectiveness right away. However, after the fifth day of your period, it’ll take up to 7 days for the pill to start working. Be sure to have other forms of BC handy (like condoms or diaphragms) during this time.

It’s a similar situation with the minipill. If you start taking it during the first 5 days of your period, you’re protected right away. Unlike the combination pill, however, it only takes the minipill 2 days to start working if you take it after the fifth day of your period.

With so many birth control options available, it’s easy to find a method of pregnancy prevention that works for you. So just how effective are the other BC methods out there? Let’s break it down.

Hormonal IUD

Less than 1 out of 100 people will get pregnant.

A hormonal intrauterine device (or IUD) is a small, T-shaped device your doctor places inside your uterus. It releases hormones to stop ovulation and prevent fertilization. Hormonal IUDs need to be replaced every 3 to 5 years to remain effective.

Copper IUD

Less than 1 out of 100 people will get pregnant.

Copper IUDs don’t use hormones, but are still able to prevent pregnancy by harming sperm that enters the uterus to prevent them from fertilizing an egg.

A copper IUD has a longer shelf-life than their hormonal counterpart, only needing to be replaced every 10 years for peak effectiveness.


Less than 1 out of 100 people will get pregnant.

Implants are small plastic rods that produce hormones that thicken cervical mucus and stop eggs from releasing. This form of hormonal birth control is placed under the skin of your upper arm by your doctor, and you will feel it. It will work for up to 3 years before needing to be replaced.


Less than 1 out of 100 people will get pregnant.

A vasectomy is a surgical procedure, where the tubes that sperm travels down to get to the semen are cut or sealed off. This will cause the partner with a penis to start shooting blanks (you’ll still ejaculate semen, just without any sperm).

It can take 3 months for a vasectomy to become fully effective, after which you’ll want to get your doc’s seal of approval that the procedure worked. Until then, it’s important to use another form of birth control if you want to steer clear of pregnancy.

Female sterilization (tubal ligation)

Less than 1 out of 100 people will get pregnant.

Sterilization by tubal ligation (aka “getting your tubes tied”) is a surgical procedure where the fallopian tubes will be cut or tied so that eggs can’t make their way to the uterus (and sperm can’t make its way to the eggs).

Keep in mind, this is a permanent procedure, so there’s no reversing if you choose you want to get pregnant after it’s been done.


6 out of 100 people will get pregnant.

Shots, like Depo-Provera, are an injected form of BC that releases hormones that stop ovulation, while thickening cervical mucus.

For max effectiveness, you need to get a shot every 12 weeks. Missing or delaying an injection can significantly increase your chances of becoming pregnant.


9 out of 100 people will get pregnant.

The patch is a stick-it and go method of birth control that’s great if you’re wanting a low maintenance method to prevent pregnancy. The patch needs to be replaced every week on the same day to remain effective.

Depending where on your body you place it, it may move around. It can also be easily affected by antibiotics or other meds. So, while the patch is fairly effective with perfect use, it has a larger margin of error with typical use that can lower its ability to protect you.

Vaginal ring

9 out of 100 people will get pregnant.

The ring releases hormones that thicken cervical mucus and suppress ovulation. It’s fairly easy to use: you simply insert it into your vagina and voila! That’s it.

Despite its ease of use, you have to be diligent to reap the ring’s full effectiveness. The ring needs to be removed every 3 weeks. You’ll also need to wait a week after removal before inserting a new ring; however, it’s important that you insert the new ring on the same day each month.


12 out of 100 people will get pregnant.

Much like a period disc, diaphragms are inserted into your vagina and rest up against the cervix to create a barrier. When it comes to perfect use, diaphragms can be a bit tricky. To properly work, they have to be inserted correctly AND you have to leave them in for 6 to 8 hours after sex, or they may not work.

Male condoms

18 out of 100 people will get pregnant.

The tried and true male condom has a high effectiveness rate in preventing pregnancy or the spread of STIs — when used correctly.

Unfortunately, there can be a broad margin of error when it comes to the condom, which can decrease its usefulness. Male condoms can become less effective if they’re worn incorrectly, are expired, or weren’t stored correctly before use.

Female condoms

21 out of 100 people will get pregnant.

Female condoms are inserted into the vagina to create a barrier, so that semen and other fluids can’t enter the uterus. Like their male counterparts, female condoms can be highly effective, but only when they’re used correctly.

Their effectiveness can decrease significantly if they aren’t properly inserted, stored wrong, are expired, or are put on after penetration has started.

Pull-out method

22 out of 100 people will get pregnant.

The pull-out (aka withdrawal) method involves a lot of self-control… and sometimes a bit of luck. For this method to work properly, you have to pull out before ejaculation to prevent any semen from entering the vagina.

While rare, sperm can also make its way into precum fluids that occur before ejaculation. Meaning even. the perfect pull-out can fail.

Cervical caps

Up to 23 out of 100 people will get pregnant.

Similar to a diaphragm, a cervical cap is placed against the cervix as a barrier. It also has quite a bit of room for error, as it must also be correctly inserted and left in for a minimum of 6 hours after sex for full effectiveness.

Fertility awareness method (FAM)

24 out of 100 people will get pregnant.

The fertility awareness method (FAM) is a natural birth control method that involves tracking your menstrual cycle to avoid sex on your most fertile days (or make sure you’re using a backup form of BC). Methods can include tracking basal body temperature, cervical fluid, and calendar cycle tracking.

Incorrect calculations or an irregular period can throw off FAM tracking, putting you at risk of pregnancy when you think you’re in the clear. It’s also more effective the more tracking methods you combine.


Up to 24 out of 100 people will get pregnant.

This soft, squishy piece of foam is inserted right into your vagina. It’s usually coated in spermicide and acts as a barrier to keep sperm out of your uterus.

The sponge has a lower level of effectiveness than other methods, even when used perfectly. To achieve perfect use, the sponge has to be inserted correctly and left in for a minimum of 6 hours after sex.


28 out of 100 people will get pregnant.

The topical of birth control methods, you can get spermicide as a cream, gel, or even a foam. While spermicide is often paired with a barrier method of BC, like a diaphragm, condom, or sponge, it can be used on its own… though it can be less effective this way.

Spermicide usually comes with an applicator to help you coat the inside of your vagina. You want to make sure you get all up in there, especially near the cervix, for the spermicide to do its thing.

It can be less effective if it isn’t inserted properly, has expired, or isn’t stored in the right way.

Real talk: the only way to guarantee you won’t get pregnant is to not have sex. But if celibacy isn’t your thing, it’s important to understand that no form of birth control is ever 100 percent effective.

If you think your birth control might have failed, emergency contraceptives, like Plan B, can be taken within 72 hours (that’s 3 days) of sex to prevent pregnancy. This method is about 75 to 89 percent effective within this timeframe. But Plan B may not be as effective if you have a body mass index (BMI) over 25.

Ella emergency contraception may be a better choice if you weigh more than 155 pounds. Planned Parenthood notes this EC method is about 85 percent effective in preventing pregnancy when taken up to 5 days after sex (but may be less effective for folks who weigh over 195 pounds).

If you’re sexually active, no method can 100 percent prevent pregnancy.

Both combination and progestin birth control pills can be up to 99 percent effective at preventing pregnancy with perfect use, and 91 percent effective with typical use. Typical use basically means you aren’t perfect — like if you occasionally miss a dose or take it at the wrong time.

Depending on your method of choice, you can get birth control prescribed by your doctor (like the pill, patch, or IUD), at your local drugstore (hey, condoms and other barrier methods!), or even online.

Just remember that nonbarrier birth control methods don’t protect you from sexually transmitted infections (STIs). Practicing safer sex can help you prevent STIs and pregnancy. That means using condoms, scheduling regular check-ups with your doc, and establishing an open dialogue with your partner about STI testing.