* Annual figures use published 2013 U.S. estimates; LAM uses a six-month estimate. Combining failure rates assumes they are independent and does not establish that a pair is safe or its real-world effectiveness. Methodology and sources.
For an estimate based on individual encounters, try the Pregnancy Chance Calculator.
Compare one method with a two-method combination. These estimates describe pregnancy prevention, not protection from sexually transmitted infections.
Understanding Typical Use vs. Perfect Use
Perfect use measures how effective a contraceptive method is when used consistently and correctly every time, without mistakes or missed uses. Typical use reflects how the method performs in real-life situations, where mistakes can happen, like a condom breaking, or forgetting to take a pill every now and then.
For example, birth control pills are 99.7% effective with perfect use, meaning about 3 out of 1,000 users may become pregnant in the first year. However, with typical use, their effectiveness drops to about 91%, resulting in about 9 pregnancies per 100 users in the first year.
In contrast, long-acting methods like the hormonal implant have similar effectiveness rates for both perfect and typical use because they require little to no user intervention once in place. On the other hand, methods such as fertility awareness have a wider gap between perfect and typical use effectiveness due to the higher potential for user error.
Since everyday use often involves inconsistencies, it's important to consider typical use rates when choosing a contraceptive method. Proper education and consistent application can help you achieve effectiveness closer to perfect use.
Using two contraceptive methods
A second method can add protection, but the effects depend on which methods you combine and how you use them.
For example, you can compare condoms with condoms plus a pill, or withdrawal while using spermicide. Do not use two condoms together.
Methodology
Annual rates come from CDC's 2013 U.S. table, adapted from Trussell (2011). They are historical population estimates. The hormonal IUD and implant rows refer to Mirena and Implanon; other products may differ. The typical-use fertility-awareness rate is a grouped estimate, not a separate measurement for each named technique.
For two methods, the arithmetic is 1 minus the product of their failure rates. It assumes independent failures, which may not hold in practice. Selecting the same method twice does not create an additional independent method. A flagged arithmetic comparison is not an estimate of pregnancy prevention.
The Family Planning Global Handbook gives about 98% effectiveness for common LAM use and more than 99% with correct use, over the first six months after birth. The perfect-use comparison uses that published boundary, not an exact rate. LAM must meet the CDC eligibility conditions.
Our calculator uses mathematical models based on published contraceptive effectiveness rates. You can choose between typical use (what happens in real life with human error) or perfect use (ideal, consistent use every time).
For example:
- Condom (typical use): 82% effective
- Birth Control Pill (typical use): 91% effective
When combined, the calculator estimates your protection using simple probability math. However, it’s important to note that not all contraceptive combinations work better together—and some may even reduce effectiveness.
👉 Learn more about this in our guide:
🔗 Contraceptive Methods You Should Never Mix
Method combinations and safety
While our calculator offers a useful estimate, it doesn't account for negative interactions between certain methods. For instance:
- Using two condoms together can make one or both split. This is different from pairing a condom with another suitable method.
- Some hormonal methods can overlap in ways that don’t add much protection but may increase side effects.
This is why we recommend using our calculator as a starting point, but always consult a healthcare provider for personalized advice.
Further reading
- 🤔 How accurate is doubling up? Find out here:
🔗 How Effective is Using Two Contraceptives at Once? - ✅ Looking for the safest combos? Check out:
🔗 Top Contraceptive Method Combinations for Maximum Protection
Time period: Annual figures describe the first year of use. LAM describes the first six months after childbirth, while its eligibility conditions hold. The calculator does not convert a six-month figure into an annual rate.
Two condoms: Do not use two external condoms or an external and internal condom at the same time. The displayed arithmetic comparison is not a safe-use recommendation or measured protection. See NHS condom guidance.
Medical Disclaimer
These population estimates cannot determine your personal pregnancy risk or whether a method is suitable for you. Ask a healthcare professional about medical concerns and method choices.
Data Privacy Disclaimer
We value your privacy. The data entered into this product is used solely for the purpose of generating your pregnancy odds estimate. We do not store nor share any personal information. All data is securely disposed of immediately after the calculation is complete to ensure the protection of our users’ privacy.