💊 Birth Control Calculator
Estimate your cumulative chance of pregnancy over a chosen time period based on the typical-use effectiveness of your birth control method.
How birth control effectiveness is measured
Birth control methods are rated by their ‘typical-use’ failure rate — the percentage of users who become pregnant within one year of real-world use, including inconsistent or imperfect use. This differs from ‘perfect-use’ rates, which reflect flawless, consistent use under ideal conditions.
How this calculator works
Select your method to use its published typical-use annual failure rate, then enter how many years you plan to rely on it. The calculator compounds the per-year success rate across that period to estimate your cumulative chance of pregnancy: Cumulative Pregnancy Chance = 1 – (1 – annual failure rate)^years.
This tool provides general educational estimates based on published population statistics, not a prediction for any individual. Effectiveness varies with correct and consistent use; consult a healthcare provider to choose and use a method appropriately.